Human tryptophan transfer ribonucleic acid synthetase. Composition, function of thiol groups, and structure of thiol peptides.
J Biol Chem
; 251(11): 3261-8, 1976 Jun 10.
Article
em En
| MEDLINE
| ID: mdl-931986
ABSTRACT
Human tryptophanyl-tRNA synthetase resembles its counterpart in Escherichia coli in quaternary structure (alpha2), but differs in molecular weight, amino acid composition, the number of thiol groups, and the relationship of the thiol groups to enzyme activity. Nevertheless, one of the thiol groups resides in a heptapeptide sequence homologous to a heptapeptide sequence containing a thiol group in the E. coli enzyme. Each subunit of the enzyme has 6 half-cystine residues, and four thiol groups are readily titrated with 5,5'-dithiobis(2-nitrobenzoic acid). Titration of these four thiol groups inactivates the enzyme, and the inactivation is partially reversible by reduction with dithiothreitol. One thiol group reacts rapidly unless L-tryptophan, ATP, and Mg2+ are present together.
Buscar no Google
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Triptofano-tRNA Ligase
/
Aminoacil-tRNA Sintetases
Limite:
Humans
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
1976
Tipo de documento:
Article