Crystal structure of E. coli arginyl-tRNA synthetase and ligand binding studies revealed key residues in arginine recognition

The arginyl-tRNA synthetase (ArgRS) catalyzes the esterification reaction between L-arginine and its cognate tRNA(Arg). Previously reported structures of ArgRS shed considerable light on the tRNA recognition mechanism, while the aspect of amino acid binding in ArgRS remains largely unexplored. Here we report the first crystal structure of E. coli ArgRS (eArgRS) complexed with L-arginine, and a series of mutational studies using isothermal titration calorimetry (ITC). Combined with previously reported work on ArgRS, our results elucidated the structural and functional roles of a series of important residues in the active site, which furthered our understanding of this unique enzyme.

Physiological and biochemical reaction of anxiety among individuals with different special characteristics under military stress / 中华健康管理学杂志

Objective To understand the difference between psychological characteristics and stress response as a result of military stress and to evaluate the rate of stress response among individuals with different psychological characteristics.Methods The State-Trait Anxiety Inventory,blood pressure,breath,pulse wave,and serum levels of lactate acid and cortisol were measured at 8 to 9 am for 372 servicemen following 15 days'training.ResultsIn 97 subjects ,the value of special characteristic anxiety Was 2-standard deviation higher than normal model(i.e.high special characteristic anxiety).and low special characteristic anxiety was found in 79.The condition anxiety of 2 standard deviation higher than normal model wag found in 172 participants.A total of 132 subjects showed significant changes in condition anxiety,serum cortisol and lactic acid,and systolic blood pressure(P＜0.01).Sixty-one or 71 subjects with high or low special characteristic anxiety experienced condition anxiety,changed serum cortisol and lactic acid,and systolic blood pressure,respectively.Conclusion Psychological characteristics may be considered as a predicting factor of stress response.