古菌型磷酸烯醇式丙酮酸羧化酶的结构，该酶易受天冬氨酸抑制。
Structure of an archaeal-type phosphoenolpyruvate carboxylase sensitive to inhibition by aspartate.
机构信息
Virginia Bioinformatics Institute, Bioinformatics and Computational Biology Graduate Program, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
出版信息
Proteins. 2011 Jun;79(6):1820-9. doi: 10.1002/prot.23006. Epub 2011 Apr 12.
The crystal structure of an archaeal-type phosphoenolpyruvate carboxylase from Clostridium perfringens has been determined based on X-ray data extending to 3 Å. The asymmetric unit of the structure includes two tetramers (each a dimer-of-dimers) of the enzyme. The precipitant, malonate, employed for the crystallization is itself a weak inhibitor of phosphoenolpyruvate carboxylase and a malonate molecule is seen in the active-site in the crystal structure. The allosteric binding sites for aspartate (an inhibitor) and glucose-6-phosphate (an activator) observed in the Escherichia coli and Zea mays phosphoenolpyruvate carboxylase structures, respectively, are not conserved in the C. perfringens structure. Aspartate inhibits the C. perfringens enzyme competitively with respect to the substrate, Mg(++.) phosphoenolpyruvate. A mechanism for inhibition is proposed based on the structure and sequence comparisons with other archaeal-type phosphoenolpyruvate carboxylases with differing sensitivity to inhibition by aspartate.
已经基于 X 射线数据确定了来自梭状芽孢杆菌的古菌型磷酸烯醇丙酮酸羧化酶的晶体结构，该数据延伸至 3 Å。结构的不对称单位包括该酶的两个四聚体（每个二聚体的二聚体）。用于结晶的沉淀剂丙二酸盐本身就是磷酸烯醇丙酮酸羧化酶的弱抑制剂，并且在晶体结构中可以看到丙二酸盐分子在活性部位。在大肠杆菌和玉米磷酸烯醇丙酮酸羧化酶结构中观察到的别构结合位点天冬氨酸（抑制剂）和葡萄糖-6-磷酸（激活剂）在梭状芽孢杆菌结构中没有保守。天冬氨酸与底物 Mg(++.)磷酸烯醇丙酮酸竞争抑制 C. perfringens 酶。基于结构和与其他对天冬氨酸抑制敏感性不同的古菌型磷酸烯醇丙酮酸羧化酶的序列比较，提出了一种抑制机制。
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