Inhibition of rat liver cathepsins B and L by the peptide aldehyde benzyloxycarbonyl-leucyl-leucyl-leucinal and its analogues

Abstract

Cathepsins B and L belong to the papain superfamily of cysteine proteases and play important roles in various physiological and pathological processes. In the course of studies on their inhibitors, we examined the inhibitory effects of the peptide aldehyde benzyloxycarbonyl-leucyl-leucyl-leucinal (ZLLLal) and its analogues. As a result, rat liver cathepsins B and L were shown to be strongly inhibited by them. The concentration required for 50% inhibition (IC 50 ) by ZLLLal was 88 nM for cathepsin B and 163 nM for cathepsin L. Moreover, various analogues of ZLLLal, including 2-furancarbonyl-, nicotinyl-, isonicotinyl-and 4-morpholinylsuccinyl-LLLals, and some acetyl-Pro (AcP)-containing analogues, AcPLLLal and AcPPLLLal, were shown to inhibit both enzymes more strongly than ZLLLal. Among them, isonicotinyl-LLLal was most inhibitory against both cathepsins B (IC 50 , 12 nM) and L (IC 50 , 20 nM). Several of these inhibitors were indicated to be somewhat more soluble in aqueous media than ZLLLal.

L-leucyl-L-leucine methyl ester does not release cysteine cathepsins to the cytosol but inactivates them in transiently permeabilized lysosomes

“…3F). Importantly, it has been reported that MG132 is also an efficient inhibitor of cysteine cathepsins (Ito et al, 2009), which we confirmed in HeLa cells using our microtiter assay for total catB/L and catC activity measurements (strategy 1) ( Fig. 3G).…”

Two inhibitors of the ubiquitin proteasome system enhance long-term memory formation upon olfactory conditioning in the honeybee (Apis mellifera)

“…Thus, the dilution factor of a substance systemically injected into a honeybee is maximally 1:70. Given this dilution factor, the effective amount of inhibitor we injected in the behavioral experiments (1 μmol l −1 :70, which is equal to 14 nmol l −1 ) was lower than the doses of MG132 and β-lactone reported to effectively inhibit the ATP-dependent Lon protease, which has an IC 50 of 20 μmol l −1 for MG132 and an IC 50 of 3 μmol l −1 for β-lactone as well as other nonproteasomal proteases reported to be affected by either MG132 or β-lactone (Granot et al, 2007;Ito et al, 2009;Ostrowska et al, 2000;Tsubuki et al, 1996).…”

“…The reason for this contradiction remains unclear. MG132 is an inhibitor of the proteasome, but also blocks other proteases (Granot et al, 2007;Ito et al, 2009;Tsubuki et al, 1996). Accordingly, one possible explanation might be that one of the other proteases affected by MG132 is responsible for the effect on LTM formation.…”

In silico design of novel gold-phosphate containing compounds as selective inhibitors of cathepsin B in neuroinflammation

“…Cathepsin B enzymatic activity is inhibited by alpha-macroglobulin from the cystatin family of inhibitors of papain-like cysteine peptidases, and by representatives of the equistatin family [24] . There are three additional groups of naturally occurring cathepsin B inhibitors: the aziridinyl peptides, peptide epoxysuccinyls, and peptide aldehydes [25,26] . Known synthetic cathepsin B inhibitors can be divided into groups of compounds, which contain either flavonoids, cyclic sulfates, or nitriles [27,28] .…”