Proteinase, cysteine

Cathepsins are intracellular proteinases that reside within lysosomes or specific intracellular granules. Cathepsins are used to degrade proteins or pqffides that are internalised from the extracellular space. Some cathepsins such as cathepsin-G or cathepsin-K may be released from the cell to degrade specific extracellular matrix proteins. All cathepsins except cathepsin-G (serine) and cathepsin-D (aspartyl) are cysteine proteinases. 

Cysteine proteinases are proteinases that utilize the terminal sulfhydral moiety of the side chain of cysteine to effect peptide bond hydrolysis. 

Allaire M, Chernaia MM, Malcolm BA, James MN (1994) Picomaviral 3C cysteine proteinases have a fold similar to chymotrypsin-Kke serine proteinases. Nature 369 72-76 Altman MD, Nalivaika EA, Prabu-Jeyabalan M, Schiffer CA, Tidor B (2008) Computational design and experimental study of tighter binding peptides to an inactivated mutant of HIV-1 protease. Proteins 70 678-694... 

Lustigman, S., Brotman, B., Huima, T., Prince, A.M. and McKerrow, J.H. (1992) Molecular-cloning and characterization of onchocystatin, a cysteine proteinase-inhibitor of Onchocerca volvulus. Journal of Biological Chemistry 267, 17339-17346. 

Brinkworth, R.I., Brindley, P.J. and Harrop, SA. (1996) Structural analysis of the catalytic site of ACCP-1, a cysteine proteinase secreted by the hookworm... 

In this laboratory, we also include the metal ion chelators EDTA (ethylene diamine tetraacetic acid binds, e.g., Mg2 1 -ions) and EGTA (ethylene glycol-bis(2-aminoethyl)-Al,iV,iV/,iV/,-tetraacetic acid binds, e.g., Ca2+-ions) in our lysis buffers. These agents help prevent phosphatase action (by the metal ion-dependent phosphatase PP2C, which is not inhibited by microcystin-LR), metal (Ca2+) dependent proteinases, and protein kinases, which require divalent cations such as Mg2 1 (and, in some cases, also Ca2+). We also use a mix of proteinase inhibitors that inhibit a broad range of proteolytic enzymes, including serine and cysteine proteinases. 

Bl. Baici, A., Gyger-Marazzi, M., and Strauli, P., Extracellular cysteine proteinase and col-lagenase activities as a consequence of tumor-host interaction in the rabbit V2 carcinoma. Invasion Metastasis 4, 13-27 (1984). 

K. V., and Sloane, B. F., Cathepsin B to cysteine proteinase inhibitor balance in metastatic cell subpopulations isolated from murine tumors. Cancer Res. 50, 6278-6284 (1990). 

A. E. Gorbalenya, E. J. Snijder, Viral Cysteine Proteinases , Perspect. Drug Discov. Design 1996, 6, 64-86. 

Crystal structure of gingipain R an Arg-specific bacterial cysteine proteinase with a caspase-like fold. EMBOJ. 1999, 18, 5453-5462. 

Based on their sequence homology, disulfide connectivity, and cysteine location within the sequence and chemistry of the reactive site. Pis can be assigned to distinct families, as classified by Laskowski and Kato. Kunitz-type, Bowman—Birk-type, Potato type I and type II, and squash inhibitors are members of these families shown in Table 3. For inhibitors not falling into these classifications more families have been proposed. Pis can also be classified by their target/mode of action. Plants have been found to express Pis that target serine proteinases, cysteine proteinases, aspartic proteinases, and metallo-proteinases. Serine and cysteine protease inhibitors are the best-studied PIs. ... 

The proteolytic enzymes are classified into endopeptidases and exopeptidases, according to their site of attack in the substrate molecule. The endopeptidases or proteinases cleave peptide bonds inside peptide chains. They recognize and bind to short sections of the substrate s sequence, and then hydrolyze bonds between particular amino acid residues in a relatively specific way (see p. 94). The proteinases are classified according to their reaction mechanism. In serine proteinases, for example (see C), a serine residue in the enzyme is important for catalysis, while in cysteine proteinases, it is a cysteine residue, and so on. 

Cathepsin K, a member of the papain superfamily of cysteine proteinases, is selectively and highly expressed in osteoclasts (Drake et al., 1996 Bromme and Okamoto, 1995). It is secreted as a 314 amino acid proenzyme containing a 99 amino acid leader sequence (Bossard et al., 1996). Cathepsin K plays an important role in bone resorption and is a potential therapeutic target for the treatment of diseases involving excessive bone loss such as osteoporosis (Veberef al., 1997). 

Sever, N., Filipic, M., Brzin, J., Lah, T. T. (2002). Effect of cysteine proteinase inhibitors on murine B16 melanoma cell invasion in vitro. Biol. Chem., 383, 839-842. 

Fig. 14. Initial interval of cleavage of HPMA copolymer based polymeric substrates by lysosomal cysteine proteinase cathepsin B (isolated from bovine spleen). Only the cleavage of the bond between the distal amino acid residue and p-nitroaniline was monitored. Conditions of cleavage [Cathepsin B] = 1.9 x 10 7 M [NAp] = 1.2 x 1(T3 M [EDTA] = 1 x 10 3 M [Cys] = 2.5 x 10 2 M 0.1 M phosphate buffer pH = 6.0 40 °C. Data from [249]...

Serine Proteinase Inhibitor I Serine Proteinase Inhibitor II Cysteine Proteinase Inhibitor Aspartic Proteinase Inhibitor Polyphenol Oxidase... 

Proteolysis-Associated Leucine Aminopeptidase Carboxypeptidase Aspartic Proteinase Cysteine Proteinase Ubiquitin-like Protein... 

Kidric, M., Fabian, H., Brzin, J., Popovic, T., and Pain, R.H. 2002. Folding, stability, and secondary structure of a new dimeric cysteine proteinase inhibitor. Biochem. Biophys. Res. Commun. 297 962-967. 

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