Biochemical characterization of human cathepsin X revealed that the enzyme is an exopeptidase, acting as carboxymonopeptidase or carboxydipeptidase

Biochemical characterization of human cathepsin X revealed that the enzyme is an exopeptidase, acting as carboxymonopeptidase or carboxydipeptidase

Author Klemencic, I Google Scholar
Carmona, Adriana Karaoglanovic Autor UNIFESP Google Scholar
Cezari, Maria Helena Sedenho Autor UNIFESP Google Scholar
Juliano, Maria Aparecida Autor UNIFESP Google Scholar
Juliano, Luiz Autor UNIFESP Google Scholar
Guncar, G. Google Scholar
Turk, D. Google Scholar
Krizaj, I Google Scholar
Turk, V Google Scholar
Turk, B. Google Scholar
Institution Jozef Stefan Inst
Universidade Federal de São Paulo (UNIFESP)
Abstract Cathepsin X, purified to homogeneity from human liver, is a single chain glycoprotein with a molecular mass of approximate to 33 kDa and pI 5.1-5.3. Cathepsin X was inhibited by stefin A, cystatin C and chicken cystatin (K(i) = 1.7-15.0 nm), but poorly or not at all by stefin B (K(i) > 250 nm) and L-kininogen, respectively. the enzyme was also inhibited by two specific synthetic cathepsin B inhibitors, CA-074 and GFG-semicarbazone. Cathepsin X was similar to cathepsin B and found to be a carboxypeptidase with preference for a positively charged Arg in P1 position. Contrary to the preference of cathepsin B, cathepsin X normally acts as a carboxymonopeptidase. However, the preference for Arg in the P1 position is so strong that cathepsin X cleaves substrates with Arg in antepenultimate position, acting also as a carboxydipeptidase. A large hydrophobic residue such as Trp is preferred in the P1' position, although the enzyme cleaved all P1' residues investigated (Trp, Phe, Ala, Arg, Pro). Cathepsin X also cleaved substrates with amide-blocked C-terminal carboxyl group with rates similar to those of the unblocked substrates. in contrast, no endopeptidase activity of cathepsin X could be detected on a series of o-aminobenzoic acid-peptidyl-N-[2,-dinitrophenyl]ethylenediamine substrates. Furthermore, the standard cysteine protease methylcoumarine amide substrates (k(cat)/K(m) approximate to 5.0 x 10(3) m(-1).s(-1)) were degraded approximate to 25-fold less efficiently than the carboxypeptidase substrates (k(cat)/K(m) approximate to 120.0 x 10(3) m(-1).s(-1)).
Keywords cathepsin
cysteine protease
carboxypeptidase
exopeptidase
cystatin
Language English
Date 2000-09-01
Published in European Journal of Biochemistry. Malden: Wiley-Blackwell, v. 267, n. 17, p. 5404-5412, 2000.
ISSN 0014-2956 (Sherpa/Romeo, impact factor)
Publisher Wiley-Blackwell
Extent 5404-5412
Origin http://dx.doi.org/10.1046/j.1432-1327.2000.01592.x
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000089101400018
URI http://repositorio.unifesp.br/handle/11600/26361

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