Preparation of some 2-phenylisopropyl-oxycarbonyl amino acids. Evaluation of their properties with particular reference to application in solid phase peptide synthesis

Natural and engineered kallikrein inhibitors: an emerging pharmacopoeia

The kallikreins and kallikrein-related peptidases are serine proteases that control a plethora of developmental and homeostatic phenomena, ranging from semen liquefaction to skin desquamation and blood pressure. The diversity of roles played by kallikreins has stimulated considerable interest in these enzymes from the perspective of diagnostics and drug design. Kallikreins already have well-established credentials as targets for therapeutic intervention and there is increasing appreciation of their potential both as biomarkers and as targets for inhibitor design. Here, we explore the current status of naturally occurring kallikrein protease-inhibitor complexes and illustrate how this knowledge can interface with strategies for rational re-engineering of bioscaffolds and design of small-molecule inhibitors.

New analogues of Cucurbita maxima trypsin inhibitor III (CMTI III) with simplified structure

Seven new analogues of trypsin inhibitor CMTI III were obtained by solid-phase peptide synthesis. Three analogues contained only two, instead of three, disulfide bridges, whereas the molecules of the next four analogues were shortened at the N- and/or C-terminus. The elimination of one disulfide bridge in CMTI III induces a decrease in the association equilibrium constants by 6-7 orders of magnitude, whereas the removal of one, two or three amino-acid residues at the N- and/or C-terminus does not significantly affect the activity.

New cyclosporin A analogue: synthesis and immunosuppressive activity

A synthetic analogue of cyclosporine A, in which an unusual amino acid (4R)-N-methyl-4-butenyl-4-methyl-L-threonine (MeBmt) is replaced with L-threonine (Thr), was synthesized by the solid phase method. Its activity in the humoral response to sheep red blood cells in vitro and in vivo in mice was practically the same as that of cyclosporine A used as a standard, whereas the analogue studied exerted a significantly stronger effect in the delayed type hypersensitivity to sheep red blood cells in mice.

Synthesis of an elastase inhibitor by monosubstitution of arginine-5 with valine at the reactive site in a trypsin inhibitor from squash seeds (CMTI III)

Using the solid-phase procedure an analog of trypsin inhibitor CMTI III containing Val5 instead of Arg5 in position P1, was synthesized. The substitution in only this one position P1 increased the affinity of synthetic inhibitor to porcine pancreatic elastase and human leukocyte elastase by the factor of 10(3) and 10(7), respectively.

Potentiation of bradykinin with synthetic peptides on guinea pig ileum

Potentiation of the activity of bradykinin on the isolated guinea pig ileum was studied using a designed test system with the synthetic peptides Leu-Val-Glu-Ser-Ser-Lys, Thr-Pro-Val-Ser-Glu-Lys, derivatives of the former coupled to the N- and C-terminals of bradykinin and two peptides with phenylalanine substituted with its isomer L-3-amino-3-phenylpropanoic acid in the 5- and 5,8-positions in bradykinin respectively. On average, two times potentiation effects were obtained at 10-6 to 10-8 M concentrations of the peptides. After elimination of the basic lysine no potentiation occurred with synthetic Leu-Val-Glu-Ser-Ser. With the [beta Phe5,8]-bradykinin a mixed sensitizing/potentiating effect was observed, suggesting that a separation of the two effects may be difficult with an intact receptor structure of this kind. This peptide was not hydrolyzed by carboxypeptidase B or chymotrypsin.