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Titolo:
N-ACETYLGLUCOSAMINE-6-PHOSPHATE DEACETYLASE FROM ESCHERICHIA-COLI - PURIFICATION AND MOLECULAR AND KINETIC CHARACTERIZATION
Autore:
SOUZA JM; PLUMBRIDGE JA; CALCAGNO ML;
Indirizzi:
NATL AUTONOMOUS UNIV MEXICO,FAC MED,DEPT BIOQUIM,POB 70-159,CIUDAD UNIV MEXICO CITY 04510 DF MEXICO NATL AUTONOMOUS UNIV MEXICO,FAC MED,DEPT BIOQUIM MEXICO CITY 04510 DFMEXICO INST BIOL PHYS CHIM,CNRS,UOR 9073 F-75005 PARIS FRANCE
Titolo Testata:
Archives of biochemistry and biophysics
fascicolo: 2, volume: 340, anno: 1997,
pagine: 338 - 346
SICI:
0003-9861(1997)340:2<338:NDFE-P>2.0.ZU;2-5
Fonte:
ISI
Lingua:
ENG
Soggetto:
GLUCOSAMINE-6-PHOSPHATE DEAMINASE; CIRCULAR-DICHROISM; FUNCTIONAL-ROLE; VICINAL THIOLS; NAG REGULON; PROTEIN; BINDING; GENES;
Keywords:
N-ACETYLGLUCOSAMINE-6-PHOSPHATE DEACETYLASE; ISO MECHANISMS; AMINO SUGAR METABOLISM; NAGA GENE; SULFHYDRYL GROUPS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
30
Recensione:
Indirizzi per estratti:
Citazione:
J.M. Souza et al., "N-ACETYLGLUCOSAMINE-6-PHOSPHATE DEACETYLASE FROM ESCHERICHIA-COLI - PURIFICATION AND MOLECULAR AND KINETIC CHARACTERIZATION", Archives of biochemistry and biophysics, 340(2), 1997, pp. 338-346

Abstract

N-Acetylglucosamine-6-phosphate deacetylase (E.C.3.5.1.25), and enzyme of the amino sugar utilization pathway, has been purified form an overproducing strain of Escherichia coli. The enzyme is a tetramer of identical 41-kDa subunits. The sedimentation coefficient of the oligomeris 6.5 s(20,w) and it has a pI of 4.9. The circular dichroism spectrum of the enzyme in the far uv range suggests that it is a protein belonging to the alpha/beta structural family. In the native enzyme, two thiols per chain are titrated with 5,5'-dithio-bis(2-nitrobenzoate) (NbS2);(4) one reacts rapidly, the other more slowly. The reaction of themore reactive sulfhydryl completely inhibits the activity of the enzyme. Three thiols, of the total of eight per subunit of the native enzyme, are modified by methyl iodide without significantly changing the kinetic parameters; the methylated enzyme becomes insensitive to NbS2 inhibition. One of the enzyme reaction products, glucosamine 6-phosphate, completely protects this thiol from NbS2 reaction. The kinetics of the deacetylase reaction have been studied both in the forward direction and in the backward direction. The reverse reaction is strongly unfavored and is probably physiologically insignificant, but it was useful for obtaining a better kinetic description of the enzyme. A sequential mechanism, with ordered release of products and a slow isomerization of the enzyme-acetate complex, is proposed. This model is supported by data from substrate and product inhibition patterns in both directions of the reaction. (C) 1997 Academic Press.

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Documento generato il 22/09/20 alle ore 13:15:49