中美科技交流的使者--访美国《科学》杂志主编埃利斯·鲁宾斯坦

作为科技工作者,世界上有两家学术杂志必须知道。一家是英国《自然》杂志,一家是美国《科学》杂志。科技界的人士认为,在《科学》杂志发表论文是一种巨大的荣誉,甚至国内一些著名大学曾立下这种规矩:谁要在《自然》或《科学》杂志上发表一篇论文,这就意味着教授、博士生导师和三居室的房子。今年9月24日,美国《科学》杂志主编埃利斯·鲁宾斯坦再次访华期间与记者见面,老朋友见面,话题自然离不开这位神奇的主编以及他领导的《科学》杂志。     

Structural basis for messenger RNA movement on the ribosome

Translation initiation is a major determinant of the overall expression level of a gene. The translation of functionally active protein requires the messenger RNA to be positioned on the ribosome such that the start/initiation codon will be read first and in the correct frame. Little is known about the molecular basis for the interaction of mRNA with the ribosome at different states of translation. Recent crystal structures of the ribosomal subunits, the empty 70S ribosome and the 70S ribosome containing functional ligands have provided information about the general organization of the ribosome and its functional centres. Here we compare the X-ray structures of eight ribosome complexes modelling the translation initiation, post-initiation and elongation states. In the initiation and post-initiation complexes, the presence of the Shine-Dalgarno (SD) duplex causes strong anchoring of the 5'-end of mRNA onto the platform of the 30S subunit, with numerous interactions between mRNA and the ribosome. Conversely, the 5' end of the 'elongator' mRNA lacking SD interactions is flexible, suggesting a different exit path for mRNA during elongation. After the initiation of translation, but while an SD interaction is still present, mRNA moves in the 3'-->5' direction with simultaneous clockwise rotation and lengthening of the SD duplex, bringing it into contact with ribosomal protein S2.     

悬索方程的计算机优化求解

论述了一种快速、精确的计算机优化求解悬索方程的方法 ,并以计算实例说明了其优越性     

荧光法测定蒜头果蛋白中Trp的含量

蒜头果蛋白(malanin)是从蒜头果种仁中分离、纯化出的一种新的植物蛋白质.以Na OH为水解液水解malanin,在激发波长225 nm,发射波长350 nm处测定色氨酸(Trp)的相对荧光强度.结果表明,malanin中Trp的含量为5.116 mg·g-1,即每分子malanin中含Trp约为4个.此结果将为酸水解测定malanin氨基酸的组成作为补充,同时也为malanin全序列的测定提供较好的参考数据.