Peptidase specificity characterization of C- and N-terminal catalytic sites of angiotensin I-converting enzyme

Peptidase specificity characterization of C- and N-terminal catalytic sites of angiotensin I-converting enzyme

Autor Araujo, M. C. Google Scholar
Melo, R. L. Google Scholar
Cesari, M. H. Google Scholar
Juliano, M. A. Google Scholar
Juliano, L. Google Scholar
Carmona, A. K. Google Scholar
Instituição Universidade Federal de São Paulo (UNIFESP)
Resumo Quenched fluorescence peptides were used to investigate the substrate specificity requirements for recombinant wild-type angiotensin I-converting enzyme (ACE) and two full-length mutants bearing a single functional active site (N- or C-domain). We assayed two series of bradykinin-related peptides flanked by o-aminobenzoic acid (Abz) and N-(2,4-dinitrophenyl)ethylenediamine (EDDnp), namely, Abz-GFSPFXQ-EDDnp and Abz-GFSPFRX-EDDnp (X = natural amino acids), in which the fluorescence appeared when Abz/EDDnp are separated by substrate hydrolysis. Abz-GFSPFFQ-EDDnp was preferentially hydrolyzed by the C-domain while Abz-GFSPFQQ-EDDnp exhibits higher N-domain specificity. Internally quenched fluorescent analogues of N-acetyl-SDKP-OH were also synthesized and assayed. Abz-SDK(Dnp)P-OH, in which Abz and Dnp (2,4-dinitrophenyl) are the fluorescent donor-acceptor pair, was cleaved at the D-K(Dnp) bond with high specificity by the ACE N-domain (k(cat)/K-m = 1.1 mu M-1 s(-1)) being practically resistant to hydrolysis by the C-domain. the importance of hydroxyl-containing amino acids at the Pt position for N-domain specificity was shown by performing the kinetics of hydrolysis of Abz-TDK(Dnp)P-OH and Abz-YDK(Dnp)P-OH. the peptides Abz-YRK(Dnp)P-OH and Abz-FRK(Dnp)P-OH which were hydrolyzed by wild-type ACE with K-m values of 5.1 and 4.0 mu M and k(cat) values of 246 and 210 s(-1), respectively, have been shown to be excellent substrates for ACE. the differentiation of the catalytic specificity of the C- and N-domains of ACE seems to depend on very subtle variations on substrate-specific amino acids. the presence of a free C-terminal carboxyl group or an aromatic moiety at the same substrate position determines specific interactions with the ACE active site which is regulated by chloride and seems to distinguish the activities of both domains.
Idioma Inglês
Data de publicação 2000-07-25
Publicado em Biochemistry. Washington: Amer Chemical Soc, v. 39, n. 29, p. 8519-8525, 2000.
ISSN 0006-2960 (Sherpa/Romeo, fator de impacto)
Publicador Amer Chemical Soc
Extensão 8519-8525
Fonte http://dx.doi.org/10.1021/bi9928905
Direito de acesso Acesso restrito
Tipo Artigo
Web of Science WOS:000088376900019
Endereço permanente http://repositorio.unifesp.br/handle/11600/26346

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