Dataset Information

Comparative behaviour of calpain and cathepsin B toward peptidyl acyloxymethyl ketones, sulphonium methyl ketones and other potential inhibitors of cysteine proteinases.

ABSTRACT: Peptidyl acyloxymethyl ketones, previously established as potent inactivators of the lysosomal cysteine proteinase cathepsin B, were evaluated against smooth-muscle calpain, a member of the family of Ca(2+)-dependent cysteine proteinases. Only modest rates of time-dependent inhibition could be achieved, even with peptidyl affinity groups optimized for calpain and linked to a carboxylate leaving group of very low pKa [2,6-(CF3)2PhCOO-, pKa 0.58]. Selective inactivation of cathespin B versus calpain was consistently observed with this type of inhibitor. Examination of other potential inhibitors revealed a rank order of potency against calpain to be: peptidyl sulphonium methyl ketones > fluoromethyl ketones, diazomethyl ketones >> acyloxymethyl ketones, an order which differs sharply from that found for cathespin B.

SUBMITTER: Pliura DH

PROVIDER: S-EPMC1131951 | biostudies-other | 1992 Dec

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:BACKGROUND: Cysteine proteinases perform multiple functions in seeds, including participation in remodelling polypeptides and recycling amino acids during maturation and germination. Currently, few details exist concerning these genes and proteins in coffee. Furthermore, there is limited information on the cysteine proteinase inhibitors which influence the activities of these proteinases. RESULTS: Two cysteine proteinase (CP) and four cysteine proteinase inhibitor (CPI) gene sequences have been identified in coffee with significant expression during the maturation and germination of coffee grain. Detailed expression analysis of the cysteine proteinase genes CcCP1 and CcCP4 in Robusta using quantitative RT-PCR showed that these transcripts accumulate primarily during grain maturation and germination/post germination. The corresponding proteins were expressed in E. coli and purified, but only one, CcCP4, which has a KDDL/KDEL C-terminal sequence, was found to be active after a short acid treatment. QRT-PCR expression analysis of the four cysteine proteinase inhibitor genes in Robusta showed that CcCPI-1 is primarily expressed in developing and germinating grain and CcCPI-4 is very highly expressed during the late post germination period, as well as in mature, but not immature leaves. Transcripts corresponding to CcCPI-2 and CcCPI-3 were detected in most tissues examined at relatively similar, but generally low levels. CONCLUSIONS: Several cysteine proteinase and cysteine proteinase inhibitor genes with strong, relatively specific expression during coffee grain maturation and germination are presented. The temporal expression of the CcCP1 gene suggests it is involved in modifying proteins during late grain maturation and germination. The expression pattern of CcCP4, and its close identity with KDEL containing CP proteins, implies this proteinase may play a role in protein and/or cell remodelling during late grain germination, and that it is likely to play a strong role in the programmed cell death associated with post-germination of the coffee grain. Expression analysis of the cysteine proteinase inhibitor genes suggests that CcCPI-1 could primarily be involved in modulating the activity of grain CP activity; while CcCPI-4 may play roles modulating grain CP activity and in the protection of the young coffee seedlings from insects and pathogens. CcCPI-2 and CcCPI-3, having lower and more widespread expression, could be more general "house-keeping" CPI genes.

Project description:The aim of the work was to identify and characterize the cysteine proteinases of bone tissue, as these enzymes appear necessary for bone resorption. Three cysteine-dependent proteolytic activities were separated from a homogenate of mouse calvaria by a fractionation procedure involving (NH4)2SO4 precipitation, gel filtration and ion-exchange chromatography. The first two are typical cathepsins B and L with respect to (1) their reactivity with anti-(cathepsin B) and anti-(cathepsin L) antibodies respectively, (2) their relative rate constants for inhibition by benzyloxycarbonyl-Phe-Phe-CHN2 and L-3-carboxy-trans-2,3-epoxypropionyl-L-leucylamido-(4-guanid ino)butane and (3) their enzymic properties, such as the higher activities of cathepsin L against collagen and gelatin as compared with cathepsin B, and the fact that benzyloxycarbonyl-Arg-Arg 4-methoxy-2-naphthylamide is hydrolysed only by cathepsin B. Cathepsin L was mainly recovered in its precursor form, as indicated by its apparent 40 kDa molecular mass and its relative stability at pH 7.2. The third enzyme is a cathepsin L-like proteinase with an apparent molecular mass of 70 kDa. It is immunoprecipitated by anti-(cathepsin L) antibodies, and appears as the 25 kDa band of mature cathepsin L in Western blots. It further resembles (pro)cathepsin L with regard to its activities against synthetic substrates and proteins such as collagen, and with regard to its response to various inhibitors. However, unlike (pro)cathepsin L, it is eluted as a 70 kDa protein on gel filtration (even in the presence of 1% Brij or 1 M-NaCl), it is stable at pH values as high as 9, and it exhibits stronger affinity for phenyl-Sepharose. It might thus result from a strong complex between mature cathepsin L and another entity that confers stability at alkaline pH and favours hydrophobic interactions. This 70 kDa activity was also detected in mouse muscle and long bones of Ca(2+)-deficient chicks but not in mouse liver, spleen or kidney.

Dataset Information

Comparative behaviour of calpain and cathepsin B toward peptidyl acyloxymethyl ketones, sulphonium methyl ketones and other potential inhibitors of cysteine proteinases.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets