Development of specific CXCR4 inhibitors possessing high selectivity indexes as well as complete stability in serum based on an anti-HIV peptide T140

We previously reported a truncated polyphemusin peptide analogue, T140, which efficiently inhibits infection of target cells by T-cell line-tropic strains of HIV-1 (X4-HIV-1) through its specific binding to a chemokine receptor, CXCR4. We have found that T140 is not stable in feline serum due to the cleavage of the C-terminal Arg,(14) indispensable for anti-HIV activity. On the other hand, a C-terminally amidated analogue of T140, TZ14004, has been found to be completely stable in incubation in the serum for 2 days. The C-terminal amide is thought to be needed for stability in serum. However, TZ14004 does not have fairly strong anti-HIV activity, but has relatively strong cytotoxicity, probably due to an increase by +1 charge from total +7 charges of T140. In our previous study, the number of total +6 charges seemed to be a suitable balance between activity and cytotoxicity. In this study, we have conducted a double-L-citrulline (Cit)-scanning study on TZ14004 based on the C-terminally amidated form in due consideration of the total net charges in the whole molecule to find novel effective CXCR4 inhibitors, TN14003 ([Cit(6)]-T140 with the C-terminal amide) and TC14012 ([Cit(6), D-Cit(8)]-T140 with the C-terminal amide), which possess high selectivity indexes (SIs) and complete stability in feline serum.


Phospho-azatyrosine, a less effective protein-tyrosine phosphatase substrate than phosphotyrosine

Azatyrosine (AzaTyr, 4) is a natural product isolated from Streptomyces chibanesis, whose structure is characterized by a nitrogen atom in the aryl ring of a tyrosyl residue. This seemingly minor modification to the tyrosyl residue results in profound physiological effects, as AzaTyr has been shown to promote permanent reversion of ras-dependent transformed cells to the normal phenotype in culture and to inhibit chemical induction of carcinogenesis in transgenic mice bearing oncogenic human ras. The mechanisms underlying these effects are not known, however ras-pathways involve an intricate balance between both protein-tyrosine kinases (PTKs) and protein-tyrosine phosphatases (PTPs). The present study was undertaken to examine the general utility of AzaTyr as a structural motif for PTP inhibitor design by examining the phospho-azatyrosine (pAzaTyr)-containing peptide Ac-Asp-Ala-Asp-Glu-pAzaTyr-Leu-amide (8) in a PTP1 enzyme system. Kinetic analysis indicated that 8 binds with a Km value of 210 microM and a catalytic turnover rate, kcat of 52 s(-1). This represents a greater than 50-fold reduction in binding affinity relative to the parent phosphotyrosine-containing peptide, indicating that the aryl nitrogen adversely affects binding affinity. The much lower PTP affinity of the pAzaTyr-containing peptide reduces the potential utility of the AzaTyr pharmacophore for PTP inhibitor design. These results are discussed from the point of view that incorporation of AzaTyr residues into proteins could result in perturbation of protein-tyrosine phosphorylation,dephosphorylation cascades that control signal transduction processes, including ras-dependent pathways.

Bioorganic & Medicinal Chemistry Letters


Conformational study of a highly specific CXCR4 inhibitor, T140, disclosing the close proximity of its intrinsic pharmacophores associated with strong anti-HIV activity

We report the solution structure of T140, a truncated polyphemusin peptide analogue that efficiently inhibits infection of target cells by T-cell line-tropic strains of HIV-1 through its specific binding to a chemokine receptor, CXCR4. Nuclear magnetic resonance analysis and molecular dynamic calculations revealed that T140 has a rigidly structured conformation constituted by an antiparallel beta-sheet and a type II' beta-turn. A protuberance is formed on one side of the beta-sheet by the side-chain functional groups of the three amino acid residues (L-3-(2-naphthyl)alanine, Tyr5 and Arg14), each of which is indispensable for strong anti-HIV activity. These findings provide a rationale to dissect the structural basis for the ability of this compound to block the interaction between CXCR4 and envelope glycoproteins from T-tropic strains of HIV-1.


Synthesis of (Z)-fluoroalkene dipeptide isosteres utilizing organocopper-mediated reduction of γ,γ-difluoro-α,β-enoates


Stereoselective synthesis of a set of two functionalized (E)-alkene dipeptide isosteres of L-amino acid-L-Glu and L-amino acid-D-Glu

Journal of the Chemical Society, Perkin Transactions 1


Pharmacophore identification of a specific CXCR4 inhibitor, T140, leads to development of effective anti-HIV agents with very high selectivity indexes

A polyphemusin peptide analogue, T22 ([Tyr(5,12), Lys7]-polyphemusin II), and its shortened potent analogues, T134 (des-[Cys(8,13), Tyr(9,12)]-[D-Lys10, Pro11, L-citrulline16]-T22 without C-terminal amide) and T140 [[L-3-(2-naphthyl)alanine3]-T134], strongly inhibit the T-cell line-tropic (T-tropic) HIV-1 infection through their specific binding to a chemokine receptor, CXCR4. T22 is an extremely basic peptide possessing five Arg and three Lys residues in the molecule. In our previous study, we found that there is an apparent correlation in the T22-related peptides between the number of total positive charges and anti-HIV activity or cytotoxicity. Here, we have conducted the conventional Ala-scanning study in order to define the anti-HIV activity pharmacophore of T140 (the strongest analogue among our compounds) and identified four indispensable amino acid residues (Arg2, Nal3, Tyr5, and Arg14). Based on this result, a series of L-citrulline (Cit)-substituted analogues of T140 with decreased net positive charges have been synthesized and evaluated in terms of anti-HIV activity and cytotoxicity. As a result, novel effective inhibitors, TC14003 and TC14005, possessing higher selectivity indexes (SIs, 50% cytotoxic concentration/50% effective concentration) than that of T140 have been developed.


Inhibition of pRb phosphorylation and cell cycle progression by an antennapedia-p16(INK4A) fusion peptide in pancreatic cancer cells


Ca2+-independent activity of Ca2+/calmodulin-dependent protein kinase II involved in stimulation of neurite outgrowth in neuroblastoma cells

We investigated the involvement of Ca(2+)-independent activity of Ca(2+)/calmodulin-dependent protein kinase II (CaM kinase II) in stimulation of neurite outgrowth. When neuroblastoma Neruo2a (Nb2a) cells expressing the alpha isoform of CaM kinase II (Nb2a/alpha cells) were stimulated by plating, they changed shape from round to flattened, and began to form neurites within 15 min. Numbers of cells bearing neurites increased from 15 min to about 2 h. Neurite length increased markedly from 30 min to 2 h after stimulation. Ca(2+)-independent activity of CaM kinase II increased immediately after stimulation, peaked at about 30 min, and then gradually decreased. Autophosphorylation of Thr-286 followed the same time course as the increase in Ca(2+)-independent activity. The autophosphorylation and appearance of Ca(2+)-independent activity preceded the formation of neurites. The effect of mutation of the autophosphorylation site in the kinase whose Thr-286 was replaced with Ala (alphaT286A kinase) or Asp (alphaT286D kinase) was examined. alphaT286A kinase was not converted to a Ca(2+)-independent form, and alphaT286D kinase had Ca(2+)-independent activity significantly as an autophosphorylated kinase. Cells expressing alphaT286A kinase did not form neurites, and were indistinguishable from control Nb2a cells. Cells expressing alphaT286D kinase had much longer neurites than Nb2a/alpha cells expressing the wild type kinase, although the initiation of neurite outgrowth was very late. These results indicated that Ca(2+)-independent activity of the kinase autophosphorylated at Thr-286 involves for neurite outgrowth.


Interactions between Local Anesthetics and Na+ Channel Inactivation Gate Peptides in Phosphatidylserine Suspensions as Studied by 1H-NMR Spectroscopy


Structural study of the sodium channel inactivation gate peptide including an isoleucine-phenylalanine-methionine motif and its analogous peptide (phenylalanine/glutamine) in trifluoroethanol solutions and SDS micelles

In order to gain insight into the gating mechanisms of Na+ channels, in particular their inactivation mechanisms, we studied the structures of the Na+ channel inactivation gate related peptide which includes the IFM (Ile-Phe-Met) motif (Ac-KKKFGGQDIFMTEEQKK-NH2; K1480-K1496 in rat brain type-IIA Na+ channels, MP-3A) and its F/Q(Gln) substituted one (MP-4A) in trifluoroethanol (TFE) solutions and sodium dodecyl sulfate (SDS) micelles using circular dichroism (CD) and 1H-NMR spectroscopies. Based on observed nuclear Overhauser effect constraints, three-dimensional structures of MP-3A and MP-4A were determined using simulated annealing molecular dynamics/ energy minimization calculations. In TFE solutions, no appreciable differences in the structure were observed using either CD or NMR spectra. In SDS micelles, however, the two peptides exhibited definitely different structures from each other. It was found that in MP-3A, residues 11488 and T1491 were spatially proximate with each other owing to hydrogen bonding between the amide proton of 11488 and the hydroxyl oxygen atom of T1491, whereas in MP-4A, F/Q substitution separated them owing to conformational changes. The solvent-accessible surfaces calculated for the structures of MP-3A and MP-4A showed that the former has a smoother interaction surface to the hydrophobic docking site than the latter. In conclusion, the conformational changes, as well as decreased hydrophobicity around the IFM motif owing to the F/Q mutation, may be one reason why F1489Q mutated channels cannot inactivate almost completely.


Stereoselective Synthesis of CF2-Substituted Phosphothreonine Mimetics and Their Incorporation into Peptides Using Newly Developed Deprotection Procedures

Stereoselective syntheses of all four stereoisomers of CF(2)-substituted nonhydrolyzable phosphothreonine derivatives (33, 39, and their enantiomers) and their incorporation into peptides are described herein. Key to the synthesis of these amino acids was construction of secondary phosphate-mimicking difluoromethylphosphonate units along with generation of two stereocenters. The former was achieved using a Cu(I)-mediated cross-coupling reaction of BrZnCF(2)P(O)(OEt)(2) (8) and beta-iodo-alpha,beta-unsaturated ester 12, with stereochemistry of both alpha- and beta-stereocenters being established using bornane-10,2-sultam as a chiral auxiliary. Diastereoselective hydrogenation of a chiral alpha,beta-unsaturated acylsultam (for the beta-center) (e.g., 16a) and subsequent stereoselective bromination (for the alpha-center of the threo derivative) or amination (for the alpha-center of erythro (allo) derivative) were utilized. Transesterification of the bromide to the benzyl ester followed by azide displacement of the halogen, then reduction of the resulting azide, followed by Boc-protection and finally removal of the benzyl group, afforded protected both L- and D-phosphothreonine mimetics (39 and its enantiomer). On the other hand, protected both L- and D-allo-phosphothreonine mimetics (33 and its enantiomer) were synthesized via transesterification of the above-mentioned amination product, followed by hydrogenolytic removal of the benzyl group. Key to utilization of these amino acid analogues in peptide synthesis was removal of ethyl protection from the difluoromethylphosphonate moiety. A two-step deprotection methodology, consisting of a combination of a first-step reagent [0.3 M BSTFA-TBAI in CH(2)Cl(2), BF(3).Et(2)O] followed by a second-step reagent [1 M TMSOTf-thioanisole in TFA, m-cresol, EDT] was developed for use in solid-phase protocols. A 12-residue Cdc (cell division cycle) 2-peptide 41, possessing two nonhydrolyzable phosphoamino acid mimetics (F(2)Pmab 6 and F(2)Pmp 4), was subjected to this deprotection procedure and was obtained in 25% yield based on the protected resin. The present synthetic method affords nonhydrolyzable phosphoamino acid mimetics-containing peptides in high yield without accompanying side reactions.


A New Practical Strategy for the Synthesis of Long-chain Phosphopeptide

A new practical strategy has been developed for the synthesis of long-chain phosphopeptide. Both the 2-chlorobenzyloxycarbonyl (CIZ) group for Lys and methyl (Me) for phosphoamino acids remained intact, while other commonly used side-chain protecting groups were cleaved quantitatively, during the reaction using a highly acidic trifluoromethanesulfonic acid (TFMSA)-based reagent system (High TFMSA: TFMSA-TFA-m-cresol=1:9:1, v/v). Selective deprotection of the CIZ and Me group-containing protected phosphopeptide resin with the High TFMSA gave a partially protected phosphopeptide fragment suitable for thioester-mediated fragment condensation. A deprotection protocol of the 9-fluorenylmethyloxycarbonyl (Fmoc) group, which evades significant side reaction toward the protected phosphoamino acid, was also developed. These two new findings enabled us to synthesize long-chain phosphopeptide via thioester-mediated fragment condensation.


Cell Adhesive Sequences in Mouse Laminin β1 Chain

Laminin-1, a major component of the basement membrane, consists of three different chains, alpha1, beta1, and gamma1. We sought to identify cell adhesive sequences from the mouse laminin beta1 chain by testing HT-1080 fibrosarcoma and B16-F10 melanoma cells for binding to 187 overlapping synthetic peptides which covered the entire chain. Fourteen peptides showed cell adhesive activities with either peptide-conjugated Sepharose beads or peptide-coated plates or both. Additional cells, including neuronal, endothelial, and salivary gland cells, showed biological responses in a cell type-specific manner. B-7, B-133, and B-160 showed the most potent cell attachment. Cell binding on three peptides (B-34, B-133, and B-160) was inhibited by EDTA. Cell adhesion to 11 of the 12 active peptides was inhibited to varying degrees by heparin. Of the 17 active peptides identified in the laminin beta1 chain in this and other studies, 8 are clustered on the amino terminal globular domain, suggesting a possible important role in cell binding for this domain that may be multifunctional. These data demonstrate that the laminin beta1 chain has multiple active sites for cell adhesion, some of which are cell-type specific.


Development of new methodology for the synthesis of functionalized α-fluorophosphonates and its practical application to the preparation of phosphopeptide mimetics


1H-NMR and Circular Dichroism Spectroscopic Studies on Changes in Secondary Structures of the Sodium Channel Inactivation Gate Peptides as Caused by the Pentapeptide KIFMK


Regiospecific ring-opening reactions of β-aziridinyl α,β-enoates with acids: application to the stereoselective synthesis of a couple of diastereoisomeric (E)-alkene dipeptide isosteres from a single β-aziridinyl α,β-enoate and to the convenient preparation of amino alcohols bearing α,β-unsaturated ester groups

Journal of the Chemical Society, Perkin Transactions 1


Induction of human leukocyte antigen (HLA)-A2-restricted and MAGE-3-gene-derived peptide-specific cytolytic T lymphocytes using cultured dendritic cells from an HLA-A2 esophageal cancer patient


A Low-Molecular-Weight Inhibitor against the Chemokine Receptor CXCR4: A Strong Anti-HIV Peptide T140

T22 ([Tyr5,12, Lys7]-polyphemusin II) is an 18-residue peptide amide, which has strong anti-HIV activity. T22 inhibits the T cell line-tropic (T-tropic) HIV-1 infection through its specific binding to a chemokine receptor CXCR4, which serves as a coreceptor for the entry of T-tropic HIV-1 strains. Herein, we report our finding of novel 14-residue CXCR4 inhibitors, T134 and T140, on the basis of the T22 structure. In the assays we examined, T140 showed the highest inhibitory activity against HIV-1 entry and the strongest inhibitory effect on the binding of an anti-CXCR4 monoclonal antibody (12G5) to CXCR4 among all the CXCR4 inhibitors that have been reported up to now.

Biochemical and Biophysical Research Communications


Cell Binding Sequences in Mouse Laminin 1 Chain


Pharmacophore identification of a chemokine receptor (CXCR4) antagonist, T22 ([Tyr5,12, Lys7]-polyphemusin II), which specifically blocks T cell-line-tropic HIV-1 infection


Downsizing of an HIV cell fusion inhibitor, T22 ([Tyr5,12, Lys7]-Polyphemusin II), with the maintenance of anti-HIV activity and solution structure


Effective lowly cytotoxic analogs of an HIV-cell fusion inhibitor, T22 ([Tyr5,12, Lys7]-polyphemusin II)


14-3-3β Protein Associates with Insulin Receptor Substrate 1 and Decreases Insulin-stimulated Phosphatidylinositol 3-Kinase Activity in 3T3L1 Adipocytes


Unambiguous Synthesis of Stromal Cell-derived Factor-1 by Regioselective Disulfide Bond Formation Using a DMSO-aqueous HCl System


Convenient one-pot synthesis of cystine-containing peptides using the trimethylsilyl chloride dimethyl sulfoxide/trifluoroacetic acid system and its application to the synthesis of bifunctional anti-HIV compounds1


Identification of Cell Binding Sequences in Mouse Laminin 1 Chain by Systematic Peptide Screening


Regio- and stereoselectivity in reactions of 2,3-cis- and trans-3-alkyl-2-vinylaziridines with organocopper reagents: Importance of 2,3-cis-stereochemistry in controlling selectivity


Palladium-Catalyzed Reductive Ring Opening with Formic Acid of Aziridines Bearing an α,β-Unsaturated Ester Group


Regiospecific ring-opening reactions of aziridines bearing an α,β-unsaturated ester group with trifluoroacetic acid or methanesulfonic acid: application to the stereoselective synthesis of (E)-alkene dipeptide isosteres


An Anti-HIV Peptide, T22, Forms a Highly Active Complex with Zn(II)


Analysis of the interaction of an anti-HIV peptide, T22 ([Tyr5, 12, Lys7]-polyphemusin II), with gp120 and CD4 by surface plasmon resonance

We have previously found that T22 ([Tyr5, 12, Lys7]-polyphemusin II) exhibits strong anti-human immunodeficiency virus (HIV) activity comparable to that of 3'-azido-2', 3'-dideoxythymidine (AZT). The inhibition mechanism of T22 on HIV-replication has not been elucidated precisely yet, and hence the target molecules of T22 have not been identified. However, our recent research suggested that T22 exerts its effect by blocking virus-cell fusion at an early stage of HIV infection and that T22 might interact with an HIV envelope protein and/or a T-cell surface protein, both of which are critical for HIV infection. In this paper we demonstrated that T22 binds specifically to both gp120 (an envelope protein of HIV) and CD4 (a T-cell surface protein) and that both bindings can be inhibited by an anti-T22 antibody, using biosensor technology (BIAcoreTM) based on the principles of surface plasmon resonance. Linearization by the BIAcoreTM system (BIAlogue software) and nonlinear least squares analysis by curve fitting with exponential equations showed that both interactions have close dissociation constants (approximately 10(-7) M). The present study suggests that T22 inhibits the virus-cell fusion process through binding to both gp120 and CD4.

Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology


Mechanism of Laminin Chain Assembly into a Triple-Stranded Coiled-Coil Structure


Interaction of an Anti-HIV Peptide, T22, with GP120 and CD4

Biochemical and Biophysical Research Communications


Conformational Analysis of Cyclic Hexapeptides Designed as Constrained Ligands for the SH2 Domain of the p85 Subunit of Phosphatidylinositol-3-OH Kinase.

The structures of the cyclic hexapeptide cyclo(-Gly-Tyr-Val-Pro-Met-Leu-) (1) and its phosphotyrosyl (pTyr) derivative cyclo[-Gly-Tyr(PO3H2)-Val-Pro-Met-Leu-] (2), designed as constrained models of a sequence that interacts with the src homology 2 (SH2) region of the p85 subunit of phosphatidylinositol-3-OH kinase (PI-3 kinase), were studied in methanol/water solutions by 500 MHz nmr spectroscopy. Compound 1 was found to exist as a 2:1 mixture of isomers about the Val-Pro bond (trans and cis prolyl) between 292-330 K in 75% CD3O(D,H)/(D,H)2O solutions. A third species of undetermined structure (ca. 5%) was also observed. Compound 2, a model of phosphorylated peptide ligand that binds to the PI-3 kinase SH2 domain, exhibited similar conformational isomerism. When either compound was dissolved in pure solvent [i.e., 100% CD3O(H,D) or (H,D)2O] the ratio of cis to trans isomers was ca 1:1. A battery of one- and two-dimensional nmr experiments at different temperatures and solvent compositions allowed a complete assignment of both the cis and trans forms of 1 and indicated the trans compound to be the major isomer. The spectral properties of the phophorylated derivative 2 paralleled those of 1, indicating like conformations for the two compounds. Analysis of rotating frame Overhauser spectroscopy data, coupling constants, amide proton temperature dependence, and amide proton exchange rates generated a set of constraints that were employed in energy minimization and molecular dynamics calculations using the CHARMM force field. The trans isomer exists with the tyrosine and C-terminal Tyr(+3) (Met) residues at opposite corners of the 18-membered ring separated by a distance of 16-18 A, in contrast with the cis isomer where the side chains of these residues are much closer in space (7-14 A). It was previously shown that the pTyr and the third amino acid C-terminal to this residue are the critical recognition elements for pTyr-peptide binding to the PI-3 kinase SH2 domain. Such cyclic structures may offer appropriate scaffolding for positioning important amino acid side chains of pTyr-containing peptides as a means of increasing their binding affinities to SH2 domains, and in turn provide a conceptual approach toward the design of SH2 domain directed peptidomimetics.


Preparation of Na-Boc 4-O-Diethylphosphono-L-azatyrosine, a Reagent Potentially Useful for the Synthesis of Signal Transduction Related Peptides.


Why Is Phosphonodifluoromethyl Phenylalanine a More Potent Inhibitory Moiety Than Phosphonomethyl Phenylalanine Toward Protein-Tyrosine Phosphatases


Identification of Cell Binding Sites in the Laminin a1 Chain Carboxyl-terminal Globular Domain by Systematic Screening of Synthetic Peptides.

The laminin alpha 1 chain carboxyl-terminal globular domain has been identified as a site of multiple biological activities. Using a systematic screening for cell binding sites with 113 overlapping synthetic peptide beads that covered this domain, we found 19 potential active sequences. Corresponding synthetic peptides were evaluated for direct cell attachment, spreading, and inhibition of cell spreading to a laminin-1 substrate using several cell lines. Five peptides (AG-10, AG-22, AG-32, AG-56, and AG-73) showed cell attachment activities with cell-type specificities. Cell spreading on AG-10 was inhibited by beta 1 and alpha 6 integrin antibodies and on AG-32 was inhibited by beta 1, alpha 2, and alpha 6 integrin antibodies. In contrast, cell adhesion and spreading on peptide AG-73 were not inhibited by these antibodies. The minimum active sequences of AG-10, AG-32, and AG-73 were determined to be SIYITRF, IAFQRN, and LQVQLSIR, respectively. These sequences are highly conserved among the different species and different laminin alpha chains, suggesting that they play a critical role for biological function and for interaction with cell surface receptors.


Synthesis of Protegrin-related Peptides and their Antibacterial and Anti-Human Immunodeficiency Virus Activity.

All disulfide analogs (types I, II and III) of protegrin (PG)-1, an 18-residue antimicrobial peptide having two intramolecular disulfide bonds, were synthesized using regioselective disulfide bond formation. Random air-oxidation of the fully reduced PG-1 formed the type III PG-1. In addition, a type III analog containing an amidated carboxy-terminal residue was also prepared. Each analog showed significant and different antibacterial and anti-human immunodeficiency virus (HIV) activity. Deletion of two disulfide bridges caused a significant decrease in activity.


Disulfide Bond-forming Reaction using Dimethyl sulfoxide/aqueous HCl System and Its Application to Regioselective Two Disulfide Bond Formation.

Disulfide bond formation in S-acetamidomethyl (Acm) cysteine-containing peptides by successive treatments with silver trifluoromethanesulfonate (AgOTf) and dimethyl sulfoxide (DMSO)/aqueous HCl is described. An S-Acm cysteine was found to be quantitatively converted into cysteine by deprotection of the Acm group with AgOTf followed by DMSO/aqueous HCl treatment. Under these reaction conditions, no significant side reactions were observed with oxidation-sensitive amino acids such as Met, Tyr and Trp. Oxytocin and a Trp-containing peptide, urotensin II, were prepared by this method. Furthermore, regioselective two disulfide bond formation was found to be feasible by the combination of air oxidation and the AgOTf-DMSO/HCl system. This strategy has been successfully applied to the syntheses of tachyplesin I and endothelin I, which have two disulfide bonds and a Trp residue in the molecule.

International Journal of Peptide and Protein Research


Synthesis and application of N-Boc-L-2-amino-4-(diethylphosphono)-4,4-difluorobutanoic acid for solid-phase synthesis of nonhydrolyzable phosphoserine peptide analogues


F2(Pmp)2-TAM3, a Novel Competitive Inhibitor of the Binding of ZAP-70 to the T Cell Antigen Receptor, Blocks Early T Cell Signaling

Signaling by the T cell antigen receptor (TCR) is mediated by 17-residue tyrosine-based activation motifs (TAM) present in the cytoplasmic tails of the TCR zeta and CD3 chains. TAMs become tyrosine-phosphorylated upon TCR stimulation, creating a high affinity binding site for the tandem SH2 domains of ZAP-70. In permeabilized T cells, the association of TCR and ZAP-70 was inhibited by a protein tyrosine phosphatase (PTPase)-resistant TAM peptide analog, in which difluorophosphonomethyl phenylalanyl (F2Pmp) residues replaced phosphotyrosine. Inhibition of this association prevented TCR-stimulated tyrosine phosphorylation of ZAP-70 and reduced ZAP-70 kinase activity to basal levels. The reduction in ZAP-70 activity coincided with reduced tyrosine phosphorylation of a number of substrates. Such PTPase-resistant peptides, capable of disrupting SH2 domain-mediated protein-protein interactions, should prove useful in further dissection of multiple signaling pathways and may serve as models for rationally designed chemotherapeutic agents for the treatment of autoimmune and neoplastic disorders.


Solution-phase synthesis of an anti-human immunodeficiency virus peptide, T22 ([Tyr5,12,Lys7]-polyphemusin II), and the modification of Trp by the p-methoxybenzyl group of Cys during trimethylsilyl trifluoromethanesulfonate deprotection.


Practical Synthesis of Phosphopeptides Using Dimethyl-protected Phosphoamino Acid Derivatives.

Journal of the Chemical Society. Chemical Communications


Aza-Payne Rearrangement of Activated 2-Aziridinemethanols and 2,3-Epoxy Amines under Basic Conditions.


SN2' Ring opening of aziridines bearing an α,β-unsaturated ester group with organocopper reagents. A new stereoselective synthetic route to (E)-alkene dipeptide isosteres.

Journal of the Chemical Society, Perkin Transactions 1


A One-pot Aza-Payne Rearrangement-Epoxide Ring Opening Reaction of 2-Aziridinemethanols: A Regio- and Stereoselective Synthetic Route to Diastereomerically Pure 1,2-Amino Alocohols.


Development of Efficient Two-Step Deprotection Methodology for Dimethyl-Protected Phosphoamino Acid-Containing Peptide Resins and Its Application to the Practical Synthesis of Phosphopeptides


Advanced Insulin Synthesis by One-pot/stepwise Disulfide Bond Formation Enabled by Acid-activated S-Protected Cysteine Sulfoxide in the Presence of Chloride Anion


Sulfoxide-mediated Cys-Trp-selective bioconjugation that enables protein labeling and peptide heterodimerization


Residue-Specific Modification Reaction Using S-Acetamidomethyl Cysteine Sulfoxide, Cys(Acm)(O)


Development of copper and iron-mediated Cys-Trp-linking reaction


A New Thiol Additive for One-pot Sequential Peptide Ligation-Desulfurization Chemistry


Deprotection of S-Acetamidomethyl Cysteine Mediated by Copper Salts


Lossen rearrangement-mediated preparation of N-glyoxylyl peptide without addition of oxidant


Preparation of protein thioesters enabled by carboxypeptidase-mediated C-terminal specific hydrazinolysis


Development and application of novel protein labeling reagent "SEAL"


Development of anti-cancer peptide based on prohibitin 2


Development of methodology for cyclic peptide synthesis using a thiol-incorporated DMAP catalyst


Development of method for deprotection of N-terminal thiazolidine derivative using copper salt for chemical protein synthesis


N-S-acyl-transfer-mediated On-resin Formation of Thioester with Practical Application to Peptide Synthesis


Sulfated glycosaminoglycans promote cell membrane penetration of arginine peptides via enthalpy-driven interactions


Effect of heparin on amyloid fibril formation of apoA-I fragment peptides


Design, synthesis and biological evaluation of SNAIL1 peptide-based lysine specific demethylase 1 inhibitors


One-pot sequential native chemical ligations using photocaged crypto-thioester


Development of N-sulfanyltehylanilide (SEAlide)-based traceable linker for enrichment and selective labeling of target proteins


Tailored Synthesis of 162-Residue S-Monoglycosylated GM2-Activator Protein (GM2AP) Analogues Applicable to the Preparation of a Protein Library


Intein-inspired amide bond processing device


Second-generation synthetic strategy of GM2-activator protein (GM2AP) analogues applicable to the preparation of a protein library


One-pot/sequential native chemical ligation using photo-responsive crypto-thioester


Preparation of peptide thioesters from naturally occuring sequences using a chemical protocol


Development of intein-inspired peptide bond processing device


N-Sulfanylethylanilide (SEAlide) peptide as a versatile intermediate for protein chemical synthesis using native chemical ligation


Development of thiol-responsive traceable linker for efficient enrichment and selective labeling of target proteins


New approach for synthesis of lactam bridged peptides using olefin metathesis on AJIPHASE®


Development of hydrogen peroxide-responsive amide bond cleavage device


Development of chemical protocols for producing peptide thioesters from naturally occurring peptide sequences


Application of peptidyl prolyl thioesters to native chemical ligation


N-Sulfanylethyl anilide linkers as peptide thioester equivalent

Peptides Across The Pacific, Proceedings of the Twenty-Third American and Sixth International Peptide Symposium


Design and synthesis of hypoxia-responsive amino acid which causes peptide bond cleavage in hypoxic cells


Convergent chemical synthesis of human GM2 activator protein analog using SEAlide chemistry


Synthesis of antagonistic peptide for putative CXCL14 receptor protein and their identification


Development of efficient synthetic protocol for Fmoc amino acid-incorporated N-sulfanylethyl-aniline linker as peptide thioester precursor


Caged ceramide which releases parent ceramide after UV-induced amide bond cleavage followed by intramolecular O-N acyl transfer


Doubly-kinetically controlled proline ligation


N-Sulfanylethylanilide peptide: a peptide thioester equivalent which can directly participate in native chemical ligation


N-Sulfanylethylanilide derivative as a peptide thioester equivalent

Proceedings of the Twenty-Second American Peptide Symposium


Synthesis of CXCL14 and its derivatives utilizing C to N or N to C directive sequential NCL protocol


Development of amide bond cleavage device with application to chemical biology use


Synthesis and biological evaluation of CXCL14 and its derivatives


Enantioselective synthesis of stimulus-responsive amino acid via pyrrolidinyl tetrazole catalyzed asymmetric -amination of aldehyde


Native chemical ligation using N-peptidyl anilide as crypto-thioester


Synthesis of nonhydrolyzable AMPylated amino acid analogues for uncovering the physiological role of AMPylation


Development of recapturable cleavable linker for efficient enrichment and specific labeling of target proteins


Development of stimulus responsive thiol releasing system for controlling activity of cysteine protease


Synthesis of cyclic peptides via on resin-intramolecular native chemical ligation followed by reductive release from resin


Influence of an amino acid sequence on kinetics of peptide bond cleavage reaction induced by a stimulus-responsive amino acid


The application of peptide thioacids to NCL-type sequential condensation of peptide fragments


Synthesis of fluoroalkene dipeptide isostere utilizing intramolecular redox reaction


Synthesis of peptide thioester using N-substituted aniline derivatives


Development of stimulus-responsive amino acid with peptide bond-cleavage ability and its application to a nucleocytoplasmic shuttle peptide


Regio- and stereoselective synthesis of (Z)-alkene cis-Xaa-Pro dipeptide mimetics


Synthesis of (Z)-alkene cis-Xaa-Pro type dipeptide isosteres using organocopper-mediated anti-SN2' reactions


Development of photo-responsive self-processing peptides


4-(Dimethylamino)phenacyl Group: New Photoremovable Protecting Group for Amines and Carboxylic Acids


Synthesis of β-Secretase Inhibitors Containing a Hydroxyethylamine Dipeptide Isostere and their Structure-activity Relationship Studies


Development of Low Molecular Weight CXCR4 Antagonists by Exploratory Structural Tuning of Cyclic Tetrapeptide-scaffolds


The Chemokine Receptor CXCR4 as a Therapeutic Target for Several Diseases Including AIDS, Cancer and Rheumatoid Arthritis


Stereoselective Synthesis of Diketopiperazine Mimmetics as Promising Scaffolds for Drug Discovery Utilizing Organocopper-Mediated anti-SN2' Reaction


New Leads of Low Molecular Weight CXCR4 Antagonists Based on Enhancement of the T140-based Pharmacophores


Development of Potent β-Secretase Inhibitors Containing a Hydroxyethylamine Dipeptide Isostere


CXCR4 Antagonists Identified as Anti-Cancer Metastatic Agents


A New Strategy for Molecular-size Reduction Bioactive Peptide, Using Two Orthogonal Libraries of Cyclic Peptided


Synthesic Studies on 7TM-GPCR (I):Lipid Bilayer Assisted Membrane Peptide Ligation


Synthesis of(E)-Alkene trans-Xaa-Pro Mimetics Using Organocopper Reagents


Synthesis of CXCR4 Antagonists,T140 Derivatives with Improved Biostability, and Their SAR Study


Development of Fusion-inhibiting Anti-HIV-1 Peptides Based on the Structure of Molecular Complex Involved in HIV-1-cell Fusion


Stereoselective Synthesis of Peptidomimetics with Hydroxyethylamine Diepetide Isosteres Utilizing Aza-Payne Rearrangement and O,N-Acyl Transfer Reactions


Acid-catalyzed Ring-opening Reactions of β-Aziridinyl-α,β-enoates and Their Application


Translocation of Basic Peptides through Human Cell Membranes


Synthesis of ψ[(E)-CH=CMe]- and ψ[(Z)-CH=CMe]-type Dipeptide Isosteres and Their Application to a Cyclic RGD Peptide


Design and Synthesis of Highly Active Anti-HIV Peptide Based on gp41-C34 Peptide


Synthesis of Fluoroalkene Dipeptide Isosteres Utilizing Organocopper or SmI2 Reagents


Synthesis of ψ[(E)-CMe=CMe]- and ψ[(E)-CMe=CH]-type Alkene Dipeptide Isosteres from a Chiral Amino Acide


Synthesis of Novel Anti-HIV Peptides Based on a CXCR4 Antagonist, T140, and Their SAR Study


Artificial Remodeling of gp41-C34 Peptide Leads to Effective HIV Fusion Inhibitor with High anti-HIV Activity


Organocopper-mediated Stereoselective Synthesis of multi-Substituted Alkene Dipeptide Isosteres and Application to cyclic RGD Peptides


Efficient Synthesis of Cyclic RGD Pseudopeptide with (E)-Alkene Dipeptide Isosteres and Its Biological Activity


Development of Specific CXCR4 Inhibitors Based on an anti-HIV peptide, T140, and Their Structure-Activity Relationship Study


Stereoselective Synthesis of CF2 or CHF-Substituted Phosphoamino Acids and Their Incorporation into Peptide


Synthesis of Fluoroalkene Dipeptide Isosteres Utilizing Organometallic Reagents


New Strategy for the Synthesis of Aspartyl Protease Inhibitor Based on "Aza-Payne Rearrangement"


Application of Ring Closing Olefin Metathesis to the Conformational Restriction of Biological Active Peptide


Identification of Biologically Active Peptides in Laminin-1


Synthesis of a CC Chemokine vMIP-II,Encoded by Kaposi's Sarcoma-associated Herpesvirus and Its Biological Activity


Synthesis of Nonhydrolyzable Phosphthreonine Derivatives and Their Practical Application to Peptide Synthesis


HIV-cell Fusion Inhibitors:T22 and Its Downsized Analogs with High Activity


Convenient Preparation of Phosphopeptide Fagments Using High TFMSA System and Its Application to Synthesis of Long Chain Phosphopeptides


Synthesis of Protected 2,3-Epoxy Amines Utilizing Aza-Payne Rearrangement of Activated 2-Aziridinemethanols Under Basic Conditions


Efficient Analog of An Anti-HIV Peptide,T22 ([Tyr5,12,Lys7]-polyphemusin II),Having Low Cytotoxicity


HIV-cell Fusin Inhibitor T22([Tyr5,12,Lys7]-polyphemusin II),and Its Related Compounds


An Anti-HIV Peptide T22 is Confirmed to Be a Selective CXCR4/Fusin Inhibitor by Comparative Inhibition Study of a Chemokine SDF-1,Synthesized by Regioselective Disulfide Bond Formation


Stereoselctive Synthesis of Two Type (E)-Alkene Dipeptide Isosteres from a Single Substrate of β-Aziridinyl-α ,β-enoate


Convenient One-pot Synthesis of Cystine-containing Peptides from Protected Peptidyl Resins and Its Application to the Synthesis of Bifunctional Anti-HIV Compounds


Ring-closing Metathesis Produced a CXCR4 Antagonist with Anti-HIV Activity


Synthesis of Nonhydrolyzable Phosphothreonine Mimetic and Its Practical Application to Peptide Synthesis


Development of New Efficient Deprotecting Methodologies for The Synthesis of Phosphoamino Acids-Containing Peptides


Identification of a Polyphemusin Analog (T22)- Zn(II) complex by Mass Spectrometric Analysis and Its Anti-HIV Activity


Synthesis and Biological Activity of Bombesin Analogues Containing (E)-Alkene Dipeptide Isosteres


Identification of Binding Proteins of an Anti-HIV Peptide,T22


Practical Phosphopeptides Synthesis Using Dimethylphosphono Amino Acids (No.2)


Assembly and Stability of Double- and Triple-stranded α-Helical Coiled-coil Structures of Laminin Peptides

Peptides: Chemistry, Structure and Biology


Development of a Practical Synthetic Methodology Using Dimethylphosphono Amino Acid for Phosphopeptides


Synthesis of Protegrin-related Peptides and their Antibacterial and Anti-HIV Activity.


Application of Ser(OPO3Me2) Derivatives to The Synthesis of Phosphoserine-containing peptide


Stereoselective Synthesis of L-Vinylglycine Derivatives


Structure-Activity Relationships of An Anti-HIV Peptide, T-22(No.2)


Synthesis and Biological Activity of Phosphatases Resistant Phosphoamino Acid Mimetics Containing Peptides


Highly Stereoselective Synthesis of (E)-Alkene Dipeptide Isosters via Organocopper Mediated 1,3-Chirality Transfer Reaction and Its Application to The Synthesis of Potent Bombesin Antagonist with No Agonistic Activity