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首页> 外文期刊>Biochemistry >The 2.1A structure of torpedo californica creatine kinase complexed with the ADP-Mg~(2+-NO_3~-Creatine Transition-state analogue complex
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The 2.1A structure of torpedo californica creatine kinase complexed with the ADP-Mg~(2+-NO_3~-Creatine Transition-state analogue complex

机译：鱼雷钙蛋白肌酸激酶与ADP-Mg〜（2 + -NO_3〜-肌酸过渡态类似物复合物）的2.1A结构

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Creatine kinase (CK) catalyzes the reversible conversion of creatine and ATP to phosphocreatine and ADP,there by helping maintain energy homesotasis in the cell.Here we report the first X-ray structure of CK bound to a transition-state analogue complex (CK-TSAC).Cocrystallization of the enzyme from Torpedo californica (TcCK) with ADP-Mg~(2+),nitrate,and creatine yieldd a homodimer,one monomer of which was liganded to a TSAC complex whle the second monomer was boudto ADP-Mg~(2+) alone.The structures of both monomers were determined to 2.1 A resolution.The creatineis located with the guanidino nitrogencis to the methyl group positioned to perform in-line attack at the gamma-phosphate of ATP-Mg~(2+),while the ADP-Mg~(2+) is in a conformation similar to that found in the TSAC-bound structure of the homologue arginine kinase (AK).Thre ligandsto Mg~(2+) are contriubted by ADP and nitrate and three by ordered water molecules.The most striking difference between the substrate-bound and TSAC-bound structures is he movement of two loops,comprising residues 60-70 and residues 323-332.In the TSAC-bound structure,bothloops move into the active site,resulting in the ositioning of two hydrophobic residues (one fromeach loop) Ile69 and Val325,near the methyl group of creatine.This apparently provides a specificity pocket for optimal creatine binding as this interaction is missing in the AK structure.In addition,the active site of the transition-state analogue complex is completely occluded from solvent,unlike the ADP-Mg~(2+)-bound monomer and the unliganded structures reported previously.
机译：肌酸激酶（CK）催化肌酸和ATP可逆转化为磷酸肌酸和ADP，从而帮助维持细胞中的能量稳态。在这里，我们报道了CK的第一个X射线结构，它与过渡态类似物（CK-用ADP-Mg〜（2+），硝酸盐和肌酸将加州鱼雷（TcCK）的酶共结晶，得到同型二聚体，其中一个单体与TSAC配合物配体，第二个单体与ADP-Mg结合单独的〜（2+）。两个单体的结构均被确定为2.1 A分辨率。肌酸与鸟嘌呤氮基位于甲基位置，对ATP-Mg〜（2+ ），而ADP-Mg〜（2+）的构型与同源精氨酸激酶（AK）的TSAC结合结构相似.Mg〜（2+）的配体由ADP和硝酸盐共同作用。三个有序水分子。与底物结合的TSAC-bo与最大的区别结构和结构是两个环的运动，包括残基60-70和残基323-332。在TSAC结合的结构中，两个环都移入了活性位点，导致两个疏水残基（每个环中一个）Ile69和Val325发生位错显然在肌酸的甲基附近提供了一个特异性口袋，因为这种相互作用在AK结构中缺失。此外，与ADP不同，过渡态类似物复合物的活性位点完全被溶剂封闭-Mg〜（2 +）-键合的单体和先前报道的未配体结构。

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