According to the State Statistics Bureau, China's consumer price index (CPI) jumped by 6.9 percent year-on-year last November, approaching the high levels seen at the end of 1996, one of the largest areas of i... According to the State Statistics Bureau, China's consumer price index (CPI) jumped by 6.9 percent year-on-year last November, approaching the high levels seen at the end of 1996, one of the largest areas of increase was the price of grain,which rose by 6.6 percent. There is no doubt the growth in CPI can be mainly attributed to soaring food prices and the diffusion effect of oil price adjustments. Large orders for grain exports have put Chinese grain suppliers under tremendous pressure. In order to solve this problem, the Finance Ministry and State Administration of Taxation together announced that 84 categories of export tax rebates on major types of grain will be eliminated.……展开更多
三磷酸腺苷结合盒式(ATP-binding cassette,ABC)输出转运体是一类典型的蛋白质分子机器,这类分子机器通过门控运动进行“向外打开”(outward-facing,OF)和“向内打开”(inward-facing,IF)构象态之间转换,从而把底物转运输出生物膜外。...三磷酸腺苷结合盒式(ATP-binding cassette,ABC)输出转运体是一类典型的蛋白质分子机器,这类分子机器通过门控运动进行“向外打开”(outward-facing,OF)和“向内打开”(inward-facing,IF)构象态之间转换,从而把底物转运输出生物膜外。尽管结构和功能的研究已取得重大进展,但对ABC输出转运体构象门控的分子机制还没有完全理解。由于全原子分子动力学存在长时间尺度问题,因此对ABC蛋白质分子构象变化不能进行完全描述。本文应用粗粒化分子动力学(CG-MD)结合改善的抽样方法,对细菌ABC输出转运体MsbA进行计算模拟研究。本文计算得到的平均力势(potential of mean force,PMF)表明,从OF构象态到IF构象态之间的转变需要经过一个“阻塞态”(occluded state,OC),即MsbA的内门和外门都是关闭的状态。这种阻塞状态对ABC输出功能的方向单一性具有重要意义。我们的CG-MD计算模拟结果显示,随着MsbA的核苷酸结合域(nucleotide binding domain,NBD)的分离,外门的关闭和内门的打开是采用高度协作的方式。基于本文的计算模拟结果,我们提出了一个与目前文献中发表的有很大不同的机械力学模型,揭示了ABC输出转运体通过构象门控运动输运底物的分子机制。展开更多
文摘 According to the State Statistics Bureau, China's consumer price index (CPI) jumped by 6.9 percent year-on-year last November, approaching the high levels seen at the end of 1996, one of the largest areas of increase was the price of grain,which rose by 6.6 percent. There is no doubt the growth in CPI can be mainly attributed to soaring food prices and the diffusion effect of oil price adjustments. Large orders for grain exports have put Chinese grain suppliers under tremendous pressure. In order to solve this problem, the Finance Ministry and State Administration of Taxation together announced that 84 categories of export tax rebates on major types of grain will be eliminated.……
基金supported by the National Natural Science Foundation of China(21073170,21273209).
文摘三磷酸腺苷结合盒式(ATP-binding cassette,ABC)输出转运体是一类典型的蛋白质分子机器,这类分子机器通过门控运动进行“向外打开”(outward-facing,OF)和“向内打开”(inward-facing,IF)构象态之间转换,从而把底物转运输出生物膜外。尽管结构和功能的研究已取得重大进展,但对ABC输出转运体构象门控的分子机制还没有完全理解。由于全原子分子动力学存在长时间尺度问题,因此对ABC蛋白质分子构象变化不能进行完全描述。本文应用粗粒化分子动力学(CG-MD)结合改善的抽样方法,对细菌ABC输出转运体MsbA进行计算模拟研究。本文计算得到的平均力势(potential of mean force,PMF)表明,从OF构象态到IF构象态之间的转变需要经过一个“阻塞态”(occluded state,OC),即MsbA的内门和外门都是关闭的状态。这种阻塞状态对ABC输出功能的方向单一性具有重要意义。我们的CG-MD计算模拟结果显示,随着MsbA的核苷酸结合域(nucleotide binding domain,NBD)的分离,外门的关闭和内门的打开是采用高度协作的方式。基于本文的计算模拟结果,我们提出了一个与目前文献中发表的有很大不同的机械力学模型,揭示了ABC输出转运体通过构象门控运动输运底物的分子机制。
