Simanshu Dhirendra K, Murthy M R N
Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2005 Jan 1;61(Pt 1):52-5. doi: 10.1107/S1744309104026429. Epub 2004 Oct 23.
In the cell, propionate is mainly formed during beta-oxidation of odd-numbered carbon-chain fatty acids, fermentation of carbohydrates and degradation of the amino acids threonine, valine, isoleucine and methionine. Recently, it has been shown that L-threonine is non-oxidatively cleaved to propionate via 2-ketobutyrate. The last step in this process, conversion of propionyl phosphate and ADP to propionate and ATP, is catalysed by propionate kinase (EC 2.7.1.-). Here, the cloning of propionate kinase (molecular weight 44 kDa) from Salmonella typhimurium with an N-terminal hexahistidine affinity tag and its overexpression in Escherichia coli are reported. Purified propionate kinase was found to cocrystallize with ADP in the hanging-drop vapour-diffusion and microbatch methods. Crystals belong to space group P3(1)21 or P3(2)21, with unit-cell parameters a = b = 111.47, c = 66.52 A. A complete data set to 2.2 A resolution has been collected using an image-plate detector system mounted on a rotating-anode X-ray generator.
在细胞中，丙酸主要在奇数碳链脂肪酸的β-氧化、碳水化合物发酵以及苏氨酸、缬氨酸、异亮氨酸和蛋氨酸的氨基酸降解过程中形成。最近的研究表明，L-苏氨酸可通过2-酮丁酸非氧化裂解生成丙酸。该过程的最后一步，即丙酰磷酸和ADP转化为丙酸和ATP，由丙酸激酶（EC 2.7.1.-）催化。在此，报道了从鼠伤寒沙门氏菌中克隆出具有N端六组氨酸亲和标签的丙酸激酶（分子量44 kDa）及其在大肠杆菌中的过表达。通过悬滴气相扩散法和微量分批法发现纯化的丙酸激酶可与ADP共结晶。晶体属于空间群P3(1)21或P3(2)21，晶胞参数a = b = 111.47，c = 66.52 Å。使用安装在旋转阳极X射线发生器上的成像板探测器系统收集了分辨率为2.2 Å的完整数据集。
