Investigation of Serine-Proteinase-Catalyzed Peptide Splicing in Analogues of Sunflower Trypsin Inhibitor 1 (SFTI-1).

Serine-proteinase-catalyzed peptide splicing was demonstrated in analogues of the trypsin inhibitor SFTI-1: both single peptides and two-peptide chains (C- and N-terminal peptide chains linked by a disulfide bridge). In the second series, peptide splicing with catalytic amount of proteinase was observed only when formation of acyl-enzyme intermediate was preceded by hydrolysis of the substrate Lys-Ser peptide bond. Here we demonstrate that with an equimolar amount of the proteinase, splicing occurs in all the two-peptide-chain analogues.

Inhibitors of Matriptase-2 Based on the Trypsin Inhibitor SFTI-1.

A series of 17 new analogues of trypsin inhibitor SFTI-1 were designed and synthesized to obtain matriptase-2 inhibitors. A number of the modified bicyclic peptides displayed much higher affinity towards matriptase-2 than towards the highly homologous matriptase-1. Replacement of Lys5 by Arg in the wild-type SFTI-1 led to an 11-fold increase in the matriptase-2 inhibitory activity.

Investigation of peptide splicing using two-peptide-chain analogs of trypsin inhibitor SFTI-1.

This study examines peptide splicing catalyzed by serine proteinases. A series of two-peptide-chain analogs of trypsin inhibitor SFTI-1 were designed and synthesized via the solid-phase method. All consisted of two peptide chains (also called N- and C-terminal fragments) joined together by one disulfide bridge.

Temperature-induced changes of HtrA2(Omi) protease activity and structure.

HtrA2(Omi), belonging to the high-temperature requirement A (HtrA) family of stress proteins, is involved in the maintenance of mitochondrial homeostasis and in the stimulation of apoptosis, as well as in cancer and neurodegenerative disorders. The protein comprises a serine protease domain and a postsynaptic density of 95 kDa, disk large, and zonula occludens 1 (PDZ) regulatory domain and functions both as a protease and a chaperone. Based on the crystal structure of the HtrA2 inactive trimer, it has been proposed that PDZ domains restrict substrate access to the protease domain and that during protease activation there is a significant conformational change at the PDZ-protease interface, which removes the inhibitory effect of PDZ from the active site.