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Titolo:
INVOLVEMENT OF GLU-264 AND ARG-235 IN THE ESSENTIAL INTERACTION BETWEEN THE CATALYTIC IMIDAZOLE AND SUBSTRATE FOR THE D-LACTATE DEHYDROGENASE CATALYSIS
Autore:
TAGUCHI H; OHTA T; MATSUZAWA H;
Indirizzi:
SCI UNIV TOKYO,FAC SCI & TECHNOL,DEPT APPL BIOSCI NODA CHIBA 278 JAPAN KOGAKUIN UNIV,DEPT APPL CHEM,SHINJUKU KU TOKYO 16391 JAPAN UNIV TOKYO,DEPT BIOTECHNOL,BUNKYO KU TOKYO 113 JAPAN
Titolo Testata:
Journal of Biochemistry
fascicolo: 4, volume: 122, anno: 1997,
pagine: 802 - 809
SICI:
0021-924X(1997)122:4<802:IOGAAI>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
SITE-DIRECTED MUTAGENESIS; LACTOBACILLUS-PLANTARUM; FORMATE DEHYDROGENASE; ESCHERICHIA-COLI; BINDING; RESOLUTION; NAD; CLONING; FAMILY; GENE;
Keywords:
ACTIVE CENTER; D-LACTATE DEHYDROGENASE; LACTOBACILLUS; STEREOSPECIFICITY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
28
Recensione:
Indirizzi per estratti:
Citazione:
H. Taguchi et al., "INVOLVEMENT OF GLU-264 AND ARG-235 IN THE ESSENTIAL INTERACTION BETWEEN THE CATALYTIC IMIDAZOLE AND SUBSTRATE FOR THE D-LACTATE DEHYDROGENASE CATALYSIS", Journal of Biochemistry, 122(4), 1997, pp. 802-809

Abstract

For Lactobacillus pentosus D-lactate dehydrogenase, the binding of 2-ketoacids is markedly stabilized through interactions between the protonated imidazole of His-296, an acid/base catalyst of the enzyme, and the carbonyl oxygen of 2-ketoacids, The replacement of Arg-235 with Gln destabilized the inhibitory binding of oxamate much more than that of formate, acetate, or propionate, and the Arg to Lys substitution specifically diminished only oxamate binding. On the other hand, replacement of a conserved Glu, Glu-264, with Gin severely impaired the enzymeactivity and markedly reduced affinity to 2-keto acids. The pH dependence of the oxamate inhibition revealed that the substitutions of Arg-235 and Glu-264 induced a great loss of the imidazole-carbonyl interaction, However, replacement of Glu-264 with Asp, another acidic amino acid, affected the enzyme function less than the Glu to Gln substitution. In addition, both the Arg-235 and Glu-264 substitutions induced marked increases in the primary isotope effect on the catalysis, suggesting that these amino acids stimulate the hydrogen transfer step in the catalysis, We concluded, therefore, that the guanidino and carboxyl groups of Arg-235 and Glu-264, respectively, cooperatively promote the essential imidazole-substrate interaction, enhancing the substrate binding and catalysis.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 26/11/20 alle ore 20:13:53