Glu101在维持八肋游仆虫中心蛋白正常构象中的作用.pdf

The Study of the Role of Glu 101 in Maintaining the Proper Conformation of Euplotes Octocarinatus Centrin Li Guoting ，Wang Zhijun ，Zhao Yaqin ，Ren Liexiang ，Yang Binsheng ﹡ Institute of Molecular Science, Chemical Biology and Molecular Engineering Laboratory of Education Ministry, Shanxi University, Taiyuan, 030006, P R China E-mail ：yangbs@ Abstract Glu is highly conserved as the first amino acid of E-helix of the EF-hand protein. In this paper, Glu 101, the first amino acid of the E-helix of the third EF-hand motif in EoCen was mutated to be Lys by the method of site direct mutation. TNS and Tb3+ were used as probes in the study of the effect of this mutation to the proper conformation of EoCen. Results indicate the mutation protein (E101K) displays an increased hydrophobic exposure surface and a different Tb3+ binding characteristic. It proves that the conformation of EoCen has been altered largely by this mutation. The general conditional binding constant of Tb3+ to the three loops of EF-hand sites I, II, III in E101K was calculated to be (5.64 ± 0.57) × 105 M-1. 3+ Keywords: Centrin Tb Fluorescence Spectra 1. Introduction The microtubule-organizing center (MTOC) is cytoplasmic organelles, encountered in almost all the eukaryotic cells and having an important role in the nucleation of the microtubules and the regulation of their dynamics[1]. In higher eukaryotes, such as humans, the centrosome functions as the MTOC. Lower organisms possess equivalent MTOCs too, notably the basal body in algae and the spindle pole body (SPB) in yeast. The composition of MTOCs is highly p