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A QM/MM study on the reaction pathway leading to 2‐Aceto‐2‐hydroxybutyrate in the catalytic cycle of AHAS
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Leslie Sánchez Gonzalo A. Jaña Eduardo J. Delgado 《Journal of computational chemistry》2014,35(6):488-494
The reaction between the intermediate 2‐hydroxyethyl‐thiamin diphosphate (HEThDP?) and 2‐ketobutyrate, in the third step of the catalytic cycle of acetodydroxy acid synthase, is addressed from a theoretical point of view by means of hybrid quantum/molecular mechanical calculations. The QM region includes one molecule of 2‐ketobutyrate, the HEThDP? intermediate, and the residues Arg 380 y Glu 139; whereas the MM region includes the rest of the protein. The study includes potential energy surface scans to identify and characterize critical points on it, transition state search and activation barrier calculations. The results show that the reaction occurs via a two‐step mechanism corresponding to the carboligation and proton transfer in the first stage; and the product release in the second step. © 2014 Wiley Periodicals, Inc. 相似文献
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We study stochastic games of resource extraction, in which the players have identical preferences. The transition probability is either non-atomic or a convex combination of transition probabilities depending on the investment with coefficients also dependent on the investment. Our approach covers the unbounded utility case, which was not examined in this class of games beforehand. We prove the existence of a stationary Markov perfect equilibrium in a non-randomised class of strategies. 相似文献
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This paper considers the problem of determining operation and maintenance schedules for a containership equipped with various subsystems during its sailing according to a pre-determined navigation schedule. The operation schedule, which specifies working time of each subsystem, determines the due-date of each maintenance activity and the maintenance schedule specifies the actual start time of each maintenance activity. The main constraints are subsystem requirements, workforce availability, working time limitation, and inter-maintenance time. To represent the problem mathematically, a mixed integer programming model is developed. Then, due to the complexity of the problem, we suggest a heuristic algorithm that minimizes the sum of earliness and tardiness between the due-date and the actual start time for each maintenance activity. Computational experiments were done on various test instances and the results are reported. In particular, a case study was done on a real instance and a significant amount of improvement is reported over the experience based conventional method. 相似文献
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Abstract The results of investigation of the quasi-Cherenkov (parametric) X-ray emission of 4.5 GeV electrons in diamond and quartz crystals are presented. A noticeable increase in X-ray photons yield has been observed under the influence of external factors (acoustic waves, temperature gradient). 相似文献
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In this paper, we show a mathematical construction of Beck–Cohen superstatistics in the Bayesian point of view with the help of the two representations of a gamma function. Furthermore, it is shown how some results for superstatistics are related to each other. 相似文献