Comparison of Inhibitory Effects of Prolinal-Containing Peptide Derivatives on Prolyl Endopeptidases from Bovine Brain and Flavobacterium

抄録

The inhibitory effects of proline-containing peptides and their derivatives on prolyl endopeptidases from Flavobacterium meningosepticum and bovine brain were compared. Replacement of the carboxyl terminal proline in N-blocked peptides with prolinal resulted in remarkable decreases in K₁ values for both prolyl endopeptidases. Further reduction of the prolinal to prolinol led to a decrease in their inhibitory effects. Z-Pro-, Z-Val-, and Suc-Pro-prolinals were similarly inhibitory for both the enzymes with K₁ values of nM order. However, the inhibitory effects of Z-Pyr-prolinal and Boc-Pro-prolinal on these enzymes were significantly distinguished: they strongly inhibited the mammalian prolyl endopeptidase with K₁ values of nM order, while the K₁ values of these compounds for the microbial enzyme were only of μM order. These results suggest that there are some structural differences in the S2 and S3 subsites between the two enzymes, though their substrate specificities are apparently indistinguishable.