scholarly journals Inhibition of aspartic proteinases by α2-macroglobulin

1989 ◽  
Vol 259 (3) ◽  
pp. 905-907 ◽  
Author(s):  
D J Thomas ◽  
A D Richards ◽  
J Kay
Keyword(s):  
Cathepsin D ◽  
Serine Proteinases ◽  
Cysteine Proteinases ◽  
Aspartic Proteinases ◽  
Protein Substrates ◽  
Cathepsin E ◽  
Α2 Macroglobulin

The effect of alpha 2-macroglobulin, one of the major antiproteinases in the plasma of vertebrates, on the action of the aspartic proteinases chymosin, cathepsin D and cathepsin E towards peptide and protein substrates at pH 6.2 was examined. Activities towards protein substrates were blocked, thus demonstrating that alpha 2-macroglobulin can inhibit aspartic proteinases, in addition to serine proteinases, cysteine proteinases and metalloproteinases.

scholarly journals The selectivity of statine-based inhibitors against various human aspartic proteinases

1990 ◽  
Vol 265 (3) ◽  
pp. 871-878 ◽  
Author(s):  
R A Jupp ◽  
B M Dunn ◽  
J W Jacobs ◽  
G Vlasuk ◽  
K E Arcuri ◽  
...  
Keyword(s):  
Cathepsin D ◽  
Aspartic Proteinase ◽  
The Other ◽  
Aspartic Proteinases ◽  
Cathepsin E ◽  
Human Renin ◽  
Endothia Parasitica ◽  
Selection Of

The interactions of five human enzymes (renin, pepsin, gastricsin, cathepsin D and cathepsin E) and the aspartic proteinase from Endothia parasitica with several series of synthetic inhibitors were examined. All of the inhibitors contained the dipeptide analogue statine or its phenylalanine or cyclohexylalanine homologues in the P1-P1′ positions. The residues occupying the peripheral sub-sites (P4 to P3′) were varied systematically and inhibitory constants were determined for the interactions with each of the proteinases. Inhibitors were elucidated that specifically inhibited human renin and did not affect any of the other human enzymes or the fungal proteinase. With suitable selection of residues to occupy individual sub-sites, effective inhibitors of specific human aspartic proteinases may now be designed.

A new selective substrate for cathepsin E based on the cleavage site sequence of α2-macroglobulin

2005 ◽  
Vol 386 (3) ◽  
pp. 299-305 ◽  
Author(s):  
Yoshiyuki Yasuda ◽  
Keiko Kohmura ◽  
Tomoko Kadowaki ◽  
Takayuki Tsukuba ◽  
Kenji Yamamoto
Keyword(s):  
Cleavage Site ◽  
Defense Mechanisms ◽  
Enzyme Concentration ◽  
Cysteine Proteinases ◽  
Peptide Substrate ◽  
Enzyme Preparations ◽  
Cathepsin E ◽  
Α2 Macroglobulin ◽  
Highly Sensitive

Abstract Cathepsin E is an intracellular aspartic proteinase of the pepsin family predominantly expressed in cells of the immune system and believed to contribute to homeostasis by participating in host defense mechanisms. Studies on its enzymatic properties, however, have been limited by a lack of sensitive and selective substrates. For a better understanding of the importance of this enzyme in vivo, we designed and synthesized a highly sensitive peptide substrate for cathepsin E based on the sequence of the specific cleavage site of α2-macroglobulin. The substrate constructed, MOCAc-Gly-Ser-Pro-Ala-Phe-Leu-Ala-Lys(Dnp)-D-Arg-NH2[where MOCAc is (7-methoxycoumarin-4-yl)acetyl and Dnp is dinitrophenyl], derived from the cleavage site sequence of human α2-macroglobulin, was the most sensitive and selective for cathepsin E, with k cat/K m values of 8–11 μM-1 S-1, whereas it was resistant to hydrolysis by the analogous aspartic proteinases cathepsin D and pepsin, as well as the lysosomal cysteine proteinases cathepsins B, L, and H. The assay allows the detection of a few fmol of cathepsin E, even in the presence of plasma and cell lysate, and gives accurate results over a wide enzyme concentration range. This substrate might represent a useful tool for monitoring and accurately quantifying cathepsin E, even in crude enzyme preparations.

Structural Differences Between Rabbit Cathepsin E and Cathepsin D

1986 ◽  
Vol 367 (1) ◽  
pp. 523-526 ◽  
Author(s):  
Claude LAPRESLE ◽  
Vida PUIZDAR ◽  
Colette PORCHON-BERTOLOTO ◽  
Elisabeth JOUKOFF ◽  
Vito TURK
Keyword(s):  
Cathepsin D ◽  
Cathepsin E ◽  
Structural Differences

Picornaviral 3C cysteine proteinases have a fold similar to chymotrypsin-like serine proteinases

Nature ◽  
1994 ◽  
Vol 369 (6475) ◽  
pp. 72-76 ◽  
Author(s):  
Marc Allaire ◽  
Maia M. Chernaia ◽  
Bruce A. Malcolm ◽  
Michael N. G. James
Keyword(s):  
Serine Proteinases ◽  
Cysteine Proteinases

scholarly journals Mechanism of the reaction of papain with substrate-derived diazomethyl ketones. Implications for the difference in site specificity of halomethyl ketones for serine proteinases and cysteine proteinases and for stereoelectronic requirements in the papain catalytic mechanism

1978 ◽  
Vol 175 (2) ◽  
pp. 761-764 ◽  
Author(s):  
K Brocklehurst ◽  
J P G Malthouse
Keyword(s):  
Catalytic Mechanism ◽  
Formation Rate ◽  
Thiol Group ◽  
Site Specificity ◽  
Serine Proteinases ◽  
Cysteine Proteinases ◽  
Cyclic Transition ◽  
Cyclic Transition State ◽  
The Difference ◽  
Diazomethyl Ketones

The reactions of papain (EC 3.4.22.2) with substrate-derived diazomethyl ketones reported by Leary, Larsen, Watanabe & Shaw [Biochemistry (1977) 16, 5857–5861] are unusual in that (i) these reagents fail to react with low-molecular-weight thiols and (ii) the rate of reaction with the papain thiol group does not decrease to near-zero values across a pKa of 4 as the pH is decreased. Existing data are shown to suggest an interpretation involving neighbouring-group participation via transient thiohemiketal formation, rate-determining protonation by imidazolium ion and alkylation on sulphur via a three-membered cyclic transition state. Implications for (a) the difference in site-specificity exhibited by halomethyl ketones in their reactions with serine proteinases and cysteine proteinases and (b) stereoelectronic requirements in the mechanism of papain-catalysed hydrolysis are discussed. The possibility of two tetrahedral intermediates between adsorptive complex and acyl-enzyme is indicated.

scholarly journals Role of thiols in degradation of proteins by cathepsins

1982 ◽  
Vol 204 (2) ◽  
pp. 471-477 ◽  
Author(s):  
T Kooistra ◽  
P C Millard ◽  
J B Lloyd
Keyword(s):  
Cathepsin D ◽  
Limited Proteolysis ◽  
Lysosomal Storage ◽  
Protein Substrates ◽  
Disulphide Bonds ◽  
Protection Method ◽  
Opening Up ◽  
Lysosome Membrane

The effects of thiols on the breakdown of 125I-labelled insulin, albumin and formaldehyde-treated albumin by highly purified rat liver cathepsins B, D, H and L at pH 4.0 and 5.5 were studied. At both pH values degradation was strongly activated by the thiols cysteamine, cysteine, dithiothreitol, glutathione and 2-mercaptoethanol, and its rate increased with increasing thiol concentration. Preincubation of the protein substrates with 5 mM-glutathione did not affect concentration. Preincubation of the protein substrates with 5 mM-glutathione did not affect the rate of degradation by cathepsin D or L, and determination of free thiol groups after incubation of the proteins in the presence of glutathione but without cathepsin showed that their disulphide bonds were stable under the incubation conditions. Sephadex G-75 chromatography of the acid-soluble products of insulin digestion by cathepsin D or L suggested that thiols can reduce disulphide bonds in proteins after limited proteolysis. The resultant opening-up of the protein structure would lead to further proteolysis, so that the two processes (proteolysis and reduction) may act synergistically. By using the osmotic protection method it was shown that, at a physiological pH, cysteamine, and its oxidized form cystamine, can cross the lysosome membrane and thus may well be the physiological hydrogen donor for the reduction of disulphides in lysosomes. The results are discussed in relation to the lysosomal storage disease cystinosis.

scholarly journals New fluorogenic substrates for assay of cathepsin D and cathepsin E

1999 ◽  
Vol 79 ◽  
pp. 118
Author(s):  
Yoshiyuki Yasuda ◽  
Akifumi Akamine ◽  
Yasuo Uchiyama ◽  
Eiki Kominami ◽  
Kenji Yamamoto
Keyword(s):  
Cathepsin D ◽  
Fluorogenic Substrates ◽  
Cathepsin E
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