Expression and mutagenesis of the novel serpin endopin 2 demonstrates a requirement for cysteine-374 for dithiothreitol-sensitive inhibition of elastase.
Biochemistry
; 39(30): 8944-52, 2000 Aug 01.
Article
em En
| MEDLINE
| ID: mdl-10913307
ABSTRACT
The primary sequence of the serpin endopin 2 predicts a reactive site loop (RSL) region that possesses high homology to bovine elastase inhibitor, suggesting inhibition of elastase. Moreover, endopin 2 possesses two cysteine residues that implicate roles for reduced Cys residue(s) for inhibitory activity. To test these predicted properties, mutagenesis and chemical modification of recombinant endopin 2 were performed to examine the influence of dithiothreitol (DTT), a reducing agent, on endopin 2 activity. Endopin 2 inhibited elastase in a DTT-dependent manner, with enhanced inhibition in the presence of DTT. The stoichiometry of inhibition in the presence of DTT occurred at a molar ratio of endopin 2 to elastase of 8/1, resulting in complete inhibition of elastase. However, a higher molar ratio (25/1) was required in the absence of DTT. DTT enhanced the formation of SDS-stable complexes of endopin 2 and elastase, a characteristic property of serpins. Site-directed mutagenesis of endopin 2, with substitution of Ala for Cys-232 or Cys-374, demonstrated that Cys-374 (but not Cys-232) was required for the DTT-sensitive nature of endopin 2. Chemical modification of Cys-374 by bis(maleimido)ethane also reduced inhibitory activity. Modified electrophoretic mobilities of mutant endopin 2 suggested the presence of intramolecular disulfide bonds; in addition, chemical modification suggested that Cys-374 influences the electrophoretic and conformational properties of endopin 2. Moreover, the reducing agent glutathione enhanced endopin 2 activity, suggesting that glutathione can function as an endogenous reducing agent for endopin 2 in vivo. These findings demonstrate the importance of Cys-374 for DTT-sensitive inhibition of elastase by endopin 2.
Buscar no Google
Coleções:
01-internacional
Temas:
Geral
Base de dados:
MEDLINE
Assunto principal:
Inibidores de Proteases
/
Elastase Pancreática
/
Serpinas
/
Cisteína
/
Ditiotreitol
Tipo de estudo:
Diagnostic_studies
/
Prognostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Revista:
Biochemistry
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
Estados Unidos