Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
ENZYMES HARBORING UNNATURAL AMINO-ACIDS - MECHANISTIC AND STRUCTURAL-ANALYSIS OF THE ENHANCED CATALYTIC ACTIVITY OF A GLUTATHIONE TRANSFERASE CONTAINING 5-FLUOROTRYPTOPHAN
Autore:
PARSONS JF; XIAO GY; GILLILAND GL; ARMSTRONG RN;
Indirizzi:
VANDERBILT UNIV,SCH MED,DEPT BIOCHEM,221 KIRKLAND HALL NASHVILLE TN 37232 VANDERBILT UNIV,SCH MED,DEPT BIOCHEM NASHVILLE TN 37232 VANDERBILT UNIV,SCH MED,DEPT CHEM NASHVILLE TN 37232 VANDERBILT UNIV,SCH MED,CTR MOL TOXICOL NASHVILLE TN 37232 UNIV MARYLAND,MARYLAND BIOTECHNOL INST,CTR ADV RES BIOTECHNOL ROCKVILLE MD 20850 NIST ROCKVILLE MD 20850
Titolo Testata:
Biochemistry
fascicolo: 18, volume: 37, anno: 1998,
pagine: 6286 - 6294
Fonte:
ISI
Lingua:
ENG
Soggetto:
NUCLEAR-MAGNETIC-RESONANCE; D-LACTATE DEHYDROGENASE; S-TRANSFERASE; ESCHERICHIA-COLI; 3-DIMENSIONAL STRUCTURE; SITE; BINDING; TYROSINE-6; PROTEINS; PRODUCT;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
34
Recensione:
Indirizzi per estratti:
Citazione:
J.F. Parsons et al., "ENZYMES HARBORING UNNATURAL AMINO-ACIDS - MECHANISTIC AND STRUCTURAL-ANALYSIS OF THE ENHANCED CATALYTIC ACTIVITY OF A GLUTATHIONE TRANSFERASE CONTAINING 5-FLUOROTRYPTOPHAN", Biochemistry, 37(18), 1998, pp. 6286-6294

Abstract

The catalytic characteristics and structure of the M1-1 isoenzyme of rat glutathione (GSH) transferase in which all four tryptophan residues in each monomer are replaced with 5-fluorotryptophan are described. The fluorine-for-hydrogen substitution does not change the interactionof the enzyme with GSH even though two tryptophan residues (Trp7 and Trp45) are involved in direct hydrogen-bonding interactions with the substrate. The rate constants for association and dissociation of the peptide, measured by stopped-flow spectrometry, remain unchanged by theunnatural amino acid. The 5-FTrp-substituted enzyme exhibits a k(cat)of 73 s(-1) as compared to 18 s(-1) for the native enzyme toward 1-chloro-2,4-dinitrobenzene. That the increase in the turnover number is due to an enhanced rate of product release in the mutant is confirmed by the kinetics of the approach to equilibrium for binding of the product, The crystal structure of the 5-FTrp-containing enzyme was solved at a resolution of 2.0 Angstrom by difference Fourier techniques. The structure reveals local conformational changes in the structural elements that define the approach to the active site which are attributed tosteric interactions of the fluorine atoms associated with 5-FTrp146 and 5-FTrp214 in domain II. These changes appear to result in the enhanced rate of product release. This structure represents the first of a protein substituted with 5-fluorotryptophan.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 03/12/20 alle ore 16:00:35