Introduction of Pro and Its Analogues in the Conserved P1  Position of Trypsin Inhibitor SFTI-1 Retains Its Inhibitory Activity

Anna      Legowska; Dawid      Debowski; Rafal      Lukajtis; Emilia      Sztabkowska; Aneta      Mizeria; Krzysztof      Brzozowski; Magdalena      Wysocka; Adam      Lesner; Krzysztof      Rolka

Abstract

A number of monocyclic SFTI-1 analogues modified in the conserved inhibitor P1 position by Pro, its L-hydroxyproline (Hyp) derivative as well as mimetics with different ring size were synthesized by the solid-phase method. Replacement of Ser6 by Pro, Hyp, and a four-member ring, L-azetidine-2-carboxylic acid (Aze), retained trypsin or chymotrypsin inhibitory activity. The determined association equilibrium constants of these analogues with a cognate enzyme were about two orders of magnitude lower than those obtained for ones with conserved Ser6. In all analogues, with the exception of one, [Phe5,Aze6]SFTI-1, the P1-P1 reactive site remained intact. The results provide first evidence that the conserved Ser in the P1 position of Bowman-Birk inhibitors can be successfully replaced by an amino acid with a secondary amine group.

Keywords: Peptides, proteinase inhibitors, SFTI-1, mimetics of Pro, BB, BBI, Fmoc, DCM, DMF/NMP, NPGB, MALDI MS, BAPNA, HPLC, Proteolytic susceptibilityPeptides, proteinase inhibitors, SFTI-1, mimetics of Pro, BB, BBI, Fmoc, DCM, DMF/NMP, NPGB, MALDI MS, BAPNA, HPLC, Proteolytic susceptibility