Biomaterial Database

The role of tryptophan residues in Escherichia coli arginyl-tRNA synthetase. 1998

Q S Zhang, and E D Wang, and Y L Wang

State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry, Academia Sinica, 320 Yue-yang Road, Shanghai 200031, China.

The effect of N-bromosuccinimide (NBS) on the activity of Escherichia coli arginyl-tRNA synthetase (ArgRS) was studied. The results showed that only one tryptophan residue was easy of access to the reagent and was closely related to enzyme activity. When all the five tryptophan residues in ArgRS were changed via site-directed mutagenesis singly into Ala, the aminoacylation activity of the Trp162 mutated enzyme decreased seriously, while the other four mutant enzymes retained almost the same activity as the native one. The oxidation of the five mutant enzymes with NBS demonstrated that only the mutation of Trp162 resulted in the loss of sensitivity to the reagent. These results strongly suggest that Trp162 is more accessible to NBS and is related to enzyme activity. Furthermore, the far-UV CD spectroscopy of the mutant enzyme ArgRS162WA showed little change in its secondary structure. Finally, studies on the kinetics of the mutant enzyme ArgRS162WA in aminoacylation reaction showed that the reduction in activity could be attributed to the decrease in the values of kcat and kcat/Km for arginine. The thermodynamic calculation indicates that this mutation causes a decrease of the binding energy by 2.7 kJ/mol. Our data suggest that Trp162 is involved in the binding of arginine and in the transition state stabilization.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D010084	Oxidation-Reduction	A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).	Redox,Oxidation Reduction
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D001974	Bromosuccinimide	A brominating agent that replaces hydrogen atoms in benzylic or allylic positions. It is used in the oxidation of secondary alcohols to ketones and in controlled low-energy brominations. (From Miall's Dictionary of Chemistry, 5th ed; Hawley's Condensed Chemical Dictionary, 12th ed,).	Succinbromimide,N-Bromosuccinimide,N Bromosuccinimide
D002942	Circular Dichroism	A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Circular Dichroism, Vibrational,Dichroism, Circular,Vibrational Circular Dichroism
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D005453	Fluorescence	The property of emitting radiation while being irradiated. The radiation emitted is usually of longer wavelength than that incident or absorbed, e.g., a substance can be irradiated with invisible radiation and emit visible light. X-ray fluorescence is used in diagnosis.
D000215	Acylation	The addition of an organic acid radical into a molecule.
D001126	Arginine-tRNA Ligase	An enzyme that activates arginine with its specific transfer RNA. EC 6.1.1.19.	Arginyl T RNA Synthetase,Arg-tRNA Ligase,Arginyl-tRNA Synthetase,Arg tRNA Ligase,Arginine tRNA Ligase,Arginyl tRNA Synthetase,Ligase, Arg-tRNA,Ligase, Arginine-tRNA,Synthetase, Arginyl-tRNA
D001426	Bacterial Proteins	Proteins found in any species of bacterium.	Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial