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Titolo:
SUBSTRATE-SPECIFICITY OF ESCHERICHIA-COLI MUTY PROTEIN
Autore:
BULYCHEV NV; VARAPRASAD CV; DORMAN G; MILLER JH; EISENBERG M; GROLLMAN AP; JOHNSON F;
Indirizzi:
SUNY STONY BROOK,DEPT PHARMACOL SCI STONY BROOK NY 11794 SUNY STONY BROOK,DEPT PHARMACOL SCI STONY BROOK NY 11794
Titolo Testata:
Biochemistry
fascicolo: 40, volume: 35, anno: 1996,
pagine: 13147 - 13156
SICI:
0006-2960(1996)35:40<13147:SOEMP>2.0.ZU;2-Q
Fonte:
ISI
Lingua:
ENG
Soggetto:
T4 ENDONUCLEASE-V; G-A MISPAIRS; CATALYTIC MECHANISM; CRYSTAL-STRUCTURE; DNA GLYCOSYLASE; FPG PROTEIN; B-DNA; 8-HYDROXYGUANINE 7,8-DIHYDRO-8-OXOGUANINE; MUTAGENIC SUBSTRATE; MAGNETIC-RESONANCE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
71
Recensione:
Indirizzi per estratti:
Citazione:
N.V. Bulychev et al., "SUBSTRATE-SPECIFICITY OF ESCHERICHIA-COLI MUTY PROTEIN", Biochemistry, 35(40), 1996, pp. 13147-13156

Abstract

The MutY protein of Escherichia coil removes mismatched deoxyadenine residues from DNA. In this study, duplex oligodeoxynucleotides containing modified bases are used as model substrates for this enzyme. In contrast to a recent report [Lu, A.-L., et al. (1995) J. Biol. Chem. 270, 23582], dA:8-oxo-dG appears to be the preferred natural substrate for MutY, as evidenced by the specificity constants (k(cat)/K-m) for dA:8-oxo-dG and dA:dG of 39 600 x 10(-6) and 383 x 10(-6) (min(-1) nM(-1)), respectively. k(cat) for the duplex containing dA:dG was highest atlower pH; the rate of cleavage for the duplex containing dA:8-oxo-dG was unaffected over a pH range of 5.5-8.0. The presence of an 8-oxo function in dG increased significantly the rate of removal of dA from all substrates tested. Replacement of dA by rA reduced the specificity constant of dA:8-oxo-dG to 294 x 10(-6) (min(-1) nM(-1)), whereas replacement of dA by 2'-O-methyladenosine virtually abolished enzymatic activity. Modifications of the dG moiety generally were better tolerated than those of dA; however, introduction of a methyl ether at the 6 position of dG produced a noncleavable substrate and replacement of dG by2'-O-methylguanosine generated a substrate with a low specificity constant. Rates of cleavage of duplexes containing dA:dC and dA:tetrahydrofuran were three orders of magnitude lower than the reference substrate. Duplexes containing a carbocyclic analog of dA were not cleaved. Amodel is proposed to explain the recognition of DNA substrates by MutY and the catalytic properties of this enzyme.

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Documento generato il 08/07/20 alle ore 07:48:42