Transition State Mimic Research Articles

Dipeptide isosteres. 1. Synthesis of dihydroxyethylene dipeptide isosteres via diastereoselective additions of alkyllithium reagents to N,N-dimethylhydrazones. Preparation of renin and HIV-1 protease inhibitor transition-state mimics

The amino and diamino dihydroxyethylene dipeptide isosteres 19a,b and 23 are important intermediates for the preparation of inhibitors of human renin and HIV-1 protease, respectively. A general synthetic strategy was developed to access both dipeptide isosteres. The key step was a diastereoselective addition of an alkyllithium reagent to an aldehyde hydrazone. Thus, isosteres 19a and 19b were synthesized by addition of either benzyllithium or (cyclohexylmethyl)lithium to (4S,5R)-2,2-dimethyl-4-(2-methylpropan-1-yl)-5-formyl-1,3-dioxolane N,N-dimethylhydrazone (4) in dietbyl ether at -10 o C. The hydrazine addition product was reduced to the amine, and the acetonide protecting group was removed

ψ(SO 2-NH) transition state isosteres of peptides. Synthesis of the glutathione disulfide analogue

▪ 6 has been synthesized starting from ethyl ( S)-2-benzyloxycarbonylamino-4-(chlorosulfonyl)butanoate and S-acetamidomethyl-L-cysteinyl-glycine ethyl ester. Compound 6 is a backbone modified analogue of glutathione disulfide containing the SO 2NH transition state mimic in place of the native γ-glutamyl-cystine CONH bond.

A concise and enantioselective synthesis of novel HIV-1 protease transition state mimics

Abstract Novel HIV-1 protease inhibitors have been prepared in a enantioselective manner via an Evans asymmetric aldol, Claisen rearrangement and iodolactonizat

Dipeptide isosteres. 2. Synthesis of hydroxyethylene dipeptide isostere diastereomers from a common γ-lactone intermediate. Preparation of renin and HIV-1 protease inhibitor transition state mimics.

A general strategy for the synthesis of the hydroxyethylene dipeptide isostere diastereomers C or D has been developed. The syntheses proceeded through a common γ-lactone intermediate A or B. The C(3α) γ-lactone diastereomer A was prepared from the N-Cbz protected α-amino aldehyde and 2-(2-isopropylpropen-2-yl)trimethylsilane in five steps. The C(3β) γ-lactone diastereomer B was obtained by kinetic protonation of the lactone enolate using malonate derivatives.

Catalytic antibody for imide hydrolysis featuring a bifunctional transition-state mimic

Catalytic antibody for imide hydrolysis featuring a bifunctional transition-state mimic

Rapamycin selectively inhibits interleukin-2 activation of p70 S6 kinase.

The macrolide rapamycin induces cell cycle G1 arrest in yeast and in mammalian cells, which suggests that an evolutionarily conserved, rapamycin-sensitive pathway may regulate entry into S phase. In mammals, rapamycin inhibits interleukin-2 receptor-induced S phase entry and subsequent T-cell proliferation, resulting in immunosuppression. Here we show that interleukin-2 selectively stimulates the phosphorylation and activation of p70 S6 kinase but not the erk-encoded MAP kinases and rsk-encoded S6 kinases. Rapamycin completely and rapidly inhibits interleukin-2-induced phosphorylation and activation of p70 S6 kinase at concentrations comparable to those blocking S phase entry of T cells (0.05-0.2 nM). The structurally related macrolide FK506 competitively antagonizes the actions of rapamycin, indicating that these effects are mediated by FKBP, which binds the transition-state mimic structure common to both rapamycin and FK506 (refs 4, 6, 9-11). The selective blockade of the p70 S6 kinase activation cascade by the rapamycin-FKBP complex implicates this signalling pathway in the regulation of T cell entry into S phase.

Nonpeptide renin inhibitors employing a novel 3-aza(or oxa)-2,4-dialkyl glutaric acid moiety as a P2/P3 amide bond replacement.

A new series of renin inhibitors has been developed. The inhibitors feature a novel replacement for the P2/P3 dipeptide moiety normally associated with renin inhibitors. The dipeptide replacement was a (2S,4S)-3-aza(or oxa)-2,4-dialkylglutaric acid amide. Extensive structure-activity relationship studies determined that optimum potency was achieved when inhibitors employed a benzyl and butyl group at the C(4) and C(2) carbon position, respectively. In addition, maximum in vitro potency was obtained when the N-terminus was functionalized by incorporating a 4-(1,3-dioxabutyl)piperidine amide. SAR data suggested that the 1,3-dioxabutyl group (methoxymethyl ether) interacted by hydrogen bonding to groups in the S4 domain of renin. This hypothesis was strengthened when a 4-butylpiperidine amide was substituted and inhibitor potency decreased dramatically. Inhibitors employing this novel dipeptide mimic were prepared by coupling the glutaric acid amides with either the transition-state mimic (2S,3R,4S)-2-amino-1-cyclohexyl-3,4-dihydroxy-6- methylheptane (18) or the hydroxyethylene dipeptide isostere. The glutaric acid amides were prepared by two general procedures. The first procedure involved the reductive amination of alpha-amino acid esters with alpha-keto esters. The second procedure involved the displacement reaction of alpha-bromo esters or acids with alpha-amino acid amides.

Kynostatin (KNI)-227 and -272, highly potent anti-HIV agents: conformationally constrained tripeptide inhibitors of HIV protease containing allophenylnorstatine.

Selective and potent HIV protease inhibitors containing allophenylnorstatine [Apns; (2S, 3S)-3-amino-2-hydroxy-4-phenylbutyric acid] as a transition-state mimic were designed and synthesized. Among them, conformationally constrained tripeptide derivatives, kynostatin (KNI)-227 and -272 (Fig. 1), exhibited highly potent antiviral activities against a wide spectrum of HIV isolates. Ready availability due to the simple synthetic procedure and the excellent antiviral properties indicate that KNI-227 and KNI-272 are promising candidates as selective anti-AIDS drugs.

KNI-102, a novel tripeptide HIV protease inhibitor containing allophenylnorstatine as a transition-state mimic.

HIV-1 protease inhibitors containing allophenylnorstatine [Apns; (2S,3S)-3-amino-2-hydroxy-4-phenylbutyric acid]-Pro (syn diastereomer) as a transition-state mimic were established to be potent and highly selective. Z-Asn-Apns-Pro-NHBut (KNI-102) is the only tripeptide exhibiting substantial anti-HIV activity and may be of minimum size for potent, selective inhibition of HIV protease. Ready availability due to its simple chemical structure and stability should make it valuable for studies of the development of metabolically stable anti-AIDS drugs.

Rational design and synthesis of a novel class of active site-targeted HIV protease inhibitors containing a hydroxymethylcarbonyl isostere. Use of phenylnorstatine or allophenylnorstatine as a transition-state mimic.

A novel class of HIV-1 protease inhibitors containing a hydroxymethylcarbonyl (HMC) isostere were designed from the substrate transition state and synthesized. Phenylnorstatine [Pns; (2R,3S)-3-amino-2-hydroxy-4-phenylbutyric acid] and the 2S diastereomer, (2S,3S)-3-amino-2-hydroxy-4-phenylbutyric acid, named allophenylnorstatine (Apns) were effective transition-state mimics, and incorporation of Pns-Pro or Apns-Pro at the P1-P1' site gave potent and specific HIV-1 protease inhibitors. In the inhibitory assays, the chemically synthesized [Ala67,95] HIV-1 protease was used.

Heterocyclic derivatives of 3-substituted-1,1,1-trifluoro-2-propanones as inhibitors of esterolytic enzymes

A series of (alkylthio)trifluoropropanones containing a heterocyclic moiety was synthesized. The compounds were tested for in vitro inhibition of four hydrolytic enzymes including insect juvenile hormone esterase (JHE), eel acetylcholinesterase (AChE), yeast lipase (LP), and bovine alpha-chymotrypsin. The I50 values ranged from 10(-3) to 10(-7) M. 3-(2-Pyridylthio)-1,1,1-trifluoro-2-propanone was found to be the most potent inhibitor as compared to the other tested heterocyclic analogues with an I50 value of 98 nM against JHE from the fifth-instar larvae of Trichoplusia ni. Results from X-ray crystallography showed that the compound exists in a tetrahedral gem-diol form stabilized by an intramolecular hydrogen bond in the solid state. X-ray crystallography of a less potent inhibitor, 3-(4-pyridylthio)-1,1,1-trifluoro-2- propanone, showed that it also exists in the hydrated form, but it lacks an intramolecular hydrogen bond. These results provide indirect support that trifluoromethyl ketones are transition-state mimic inhibitors of esterases, and the bearing of the results on the transition-state mimic theory is discussed. The I50 values against AChE were in the micromolar range. Compounds containing a imidazolyl, triazolyl, and pyrimidyl moiety showed the highest inhibition of this enzyme. Differential selectivity of inhibition was associated with the bond distances between the nitrogen and the carbonyl group as in the natural substrate, when measured in the molecules in their minimal energy conformations. Inhibition of LP was moderate to weak, when compared to JHE and AChE. None of the tested compounds showed significant inhibition of alpha-chymotrypsin.(ABSTRACT TRUNCATED AT 250 WORDS)

Synthesis of human renin inhibitory peptides, angiotensinogen transition-state analogs containing a Retro-inverso amide bond.

The experimental details for the synthesis of human renin inhibitors are described. In order to avoid metabolic degradation of the Phe-His (P3-P2) amide bond in transition-state analogs, structurally modified acyl residues (P4-P3) were incorporated into the inhibitors. Compound 1a, which contained 2-(1-naphthylmethyl)-3-(N-phenethylcarbamoyl)propionyl residue (P4-P3) with a retro-inverso amide bond, L-histidine, and norstatine isoamylamide residue (P1-P1) as a transition-state mimic, had potent human renin inhibitory activity, and it lowered blood pressure when administered orally to common marmosets.

Diastereoselective Synthesis of the Hydroxyethylene Dipeptide Isostere of Leu–Val

Abstract The synthesis of hydroxyethylene dipeptide isostere of Leu–Val, a transition-state mimic, is described. The key steps of this synthetic approach are the homogeneous asymmetric hydrogenation of γ-keto esters by BINAP–Ru(II) complex, and the construction of a 2(S)-isopropyl unit.

Synthesis of the dipeptide hydroxyethylene isostere of Leu-Val, a transition state mimic for the control of enzyme function

Synthesis of the dipeptide hydroxyethylene isostere of Leu-Val, a transition state mimic for the control of enzyme function

Structure-conformation-activity relationships of renin inhibitory peptides having P 1-P 1' Xaaψ[CH 2NH]Yaa substitutions: molecular modeling and crystallography studies 1

Structure-activity studies of angiotensinogen (ANG)-based renin inhibitors having carboxy-terminal pseudodipeptidyl P 1-P 1' Xaaψ(CH 2NH]Yaa-NH 2 and related transition state synthetic mimetics were performed and integrated with molecular modeling using a computer simulated human renin active site model, and compared to a known crystallographic structure of a P 1-P 1' PheΨ[CH 2NH]Phe substituted renin inhibitor bound to rhizopuspepsin. Renin is an aspartic acid protease (EC 3.4.99.19) which catalyzes the first and rate-limiting step of the enzyme cascade that exists for the biosynthesis of angiotensin II (ANG II) 2–4. Renin inhibition may be therapeutically important in the development of useful antihypertensive agents 5–9 based on the role of the renin-angiotensin converting enzyme cascade in the physiological and, perhaps, pathophysiological control of blood pressure and electrolyte homeostasis. In retrospect, the development of ANG-based inhibitors of human renin has essentially focused on systematic structure-activity studies 10–20 related to p 1-p 1' pseudodipeptidyl substitutions of the Leu-Val cleavage site (see below) of various substrate fragments in which the scissile amide (CONH) has been replaced by CH(OH)CH 2 or CH 2NH type transition state mimics of the proposed aminol (C(OH) 2NH) that is believed to be generated during enzyme-catalyzed hydrolysis of ANG at the renin active site.

Renin inhibitors. Dipeptide analogues of angiotensinogen incorporating transition-state, nonpeptidic replacements at the scissile bond.

A series of dipeptide analogues of angiotensinogen have been prepared and evaluated for their ability to inhibit the aspartic proteinase renin. The compounds were derived from the renin substrate by replacing the scissile amide bond with a transition-state mimic and by incorporating bioisosteric replacements for the Val-10 amide bond. Analogue 21a exhibited an IC50 of 7.6 nM against purified human renin, showed high specificity for this enzyme, and produced a hypotensive response in anesthetized, salt-depleted cynomolgus monkeys.