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Titolo:
COORDINATION OF ZN2- INVOLVEMENT OF HIS-IMIDAZOLE( (AND CD2+) BY PROKARYOTIC METALLOTHIONEIN )
Autore:
DANIELS MJ; TURNERCAVET JS; SELKIRK R; SUN HZ; PARKINSON JA; SADLER PJ; ROBINSON NJ;
Indirizzi:
UNIV NEWCASTLE UPON TYNE,SCH MED,DEPT BIOCHEM & GENET NEWCASTLE TYNE NE2 4HH TYNE & WEAR ENGLAND UNIV NEWCASTLE UPON TYNE,SCH MED,DEPT BIOCHEM & GENET NEWCASTLE TYNE NE2 4HH TYNE & WEAR ENGLAND UNIV EDINBURGH,DEPT CHEM EDINBURGH EH9 3JJ MIDLOTHIAN SCOTLAND
Titolo Testata:
The Journal of biological chemistry
fascicolo: 36, volume: 273, anno: 1998,
pagine: 22957 - 22961
SICI:
0021-9258(1998)273:36<22957:COZIOH>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
METAL-BINDING PROPERTIES; ESCHERICHIA-COLI; EXPRESSED PROTEIN; ZINC-FINGER; DNA-BINDING; RECEPTOR; METALLOPROTEINS; SENSITIVITY; CADMIUM; DOMAIN;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
31
Recensione:
Indirizzi per estratti:
Citazione:
M.J. Daniels et al., "COORDINATION OF ZN2- INVOLVEMENT OF HIS-IMIDAZOLE( (AND CD2+) BY PROKARYOTIC METALLOTHIONEIN )", The Journal of biological chemistry, 273(36), 1998, pp. 22957-22961

Abstract

In mammalian metallothionein Zn2+ is exclusively coordinated to Cys-thiolate to form clusters in which the metal is thermodynamically stable but also kinetically labile, By contrast, little is known about coordination to prokaryotic metallothionein, SmtA, 3 nmol of Zn2+ nmol(-1)SmtA were displaced by 8 nmol of p-(hydroxymercuri)phenylsulfonate implicating eight of the nine Cys in the coordination of three metal ions. None of the Zn2+ associated with SmtA was accessible to 4-(2-pyridylazo)resorcinol prior to the addition of p-(hydroxymercuri)phenylsulfonate. An unusual feature of SmtA is the presence of three His residues, and we have investigated whether these contribute to metal coordination. Less Zn2+ was associated with purified SmtA(H40R/H49R/H55R), in which all three His residues were substituted with Arg, and approximately one equivalent of Zn2+ was immediately accessible to 4-(2-pyridylazo)resorcinol. Following incubation of SmtA with Cd-111, three Cd-111 resonances were detected, two in a range expected for CdS4 and the third indicative of either CdNS3 or CdN2S2 coordination. Two-dimensional TOCSY H-1 NMR and Cd-111-edited H-1 NMR showed two His residues bound to Cd-111, confirming CdN2S2 coordination. The pH of half-dissociation of Zn2+ increased from 4.05 for SmtA to 5.37 for SmtA(H40R/H49R/H55R),Equivalent values for single His mutants SmtA(H40R), SmtA(H49R), and SmtA(H55R) were 4.62, 4.48, and 3.81, respectively, revealing that conversion of His(40) or His(49) to Arg impairs Zn2+ binding at the CdN2S2 and CdS4 sites. Only approximately two equivalents of Zn2+ were associated with purified SmtA(H49R), The appearance of a fourth Cd-111 resonance at lower pH suggests that an alternative CdN2S2 site also exists.

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Documento generato il 05/07/20 alle ore 09:25:41