STRUCTURE OF CALMODULIN REFINED AT 2.2 A RESOLUTION
STRUCTURE OF CALMODULIN REFINED AT 2.2 A RESOLUTION
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DOI：
10.1016/0022-2836(88)90608-0
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发表时间：
1988-11-05
影响因子：
5.6
通讯作者：
COOK, WJ
中科院分区：
文献类型：
--
作者：
BABU, YS;BUGG, CE;COOK, WJ
哺乳动物钙调素的晶体结构在2.2 . ang处被细化。(1 .ANG。= 0.1 nm)分辨率的约束最小二乘法。最后的晶体学r因子，基于6685反射在2.2 . ang.ltoreq范围内。d .ltoreq。5.0 .ANG。强度超过2.5 σ。，等于0.175。分子中的键长和键角与理想值的均方根偏差为0.016 . ang。和1.7度。精细模型包括残基5到147，每分子钙调蛋白4个Ca2+和69个水分子。残基1至4和148的电子密度定义不明确，它们不包括在模型中。这种分子的形状有点像哑铃，总长度为65毫米。在美国，两个耳垂由一个七圈螺旋连接。突出的次级结构特征包括7。-螺旋，四个Ca2+结合环，以及两个短的，双标准的反平行β -片在相邻的Ca2+结合环之间。钙调蛋白中的四个Ca2+结合结构域具有典型的EF型构象（螺旋-环-螺旋），与其他Ca2+结合蛋白相似。钙调素的x射线结构测定显示，在分子的每一半有一个大的疏水性裂缝。这些疏水区域可能代表了与许多已知与钙调蛋白结合的药理学药物相互作用的位点。
The crystal structure of mammalian calmodulin has been refined at 2.2 .ANG. (1 .ANG. = 0.1 nm) resolution using a restrained least-squares method. The final crystallographic R-factor, based on 6685 reflections in the range 2.2 .ANG. .ltoreq. d .ltoreq. 5.0 .ANG. with intensities exceeding 2.5 .sigma., is 0.175. Bond lengths and bond angles in the molecule have root-mean-square deviations from ideal values of 0.016 .ANG. and 1.7.degree., respectively. The refined model includes residues 5 to 147, four Ca2+ and 69 water molecules per molecule of calmodulin. The electron density for residues 1 to 4 and 148 is poorly defined, and they are not included in the model. The molecule is shaped somewhat like a dumbbell, with an overall length of 65 .ANG., the two lobes are connected by a seven-turn .alpha.-helix. Prominent secondary structural features include seven .alpha.-helices, four Ca2+-binding loops, and two short, double-standard antiparallel beta-sheets between pairs of adjacent Ca2+-binding loops. The four Ca2+-binding domains in calmodulin have a typical EF had conformation (helix-loop-helix) and are similar to those described in other Ca2+-binding proteins. The X-ray structure determination of calmodulin shows a large hydrophobic cleft in each half of the molecule. These hydrophobic regions probably represent the sites of interaction with many of the pharmacological agents known to bind to calmodulin.