STRUCTURE OF A TRICLINIC TERNARY COMPLEX OF HORSE LIVER ALCOHOL-DEHYDROGENASE AT 2.9 A RESOLUTION
STRUCTURE OF A TRICLINIC TERNARY COMPLEX OF HORSE LIVER ALCOHOL-DEHYDROGENASE AT 2.9 A RESOLUTION
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DOI：
10.1016/0022-2836(81)90047-4
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发表时间：
1981-01-01
影响因子：
5.6
通讯作者：
JONES, TA
中科院分区：
文献类型：
--
作者：
EKLUND, H;SAMAMA, JP;JONES, TA
肝脏酒精脱氢酶、还原性辅酶NADH和抑制剂二甲亚砜之间的三联体复合物的结构测定为2.9 . ang。使用同构替换方法的解析。重原子位置是通过分子置换法得到的，该方法使用的相位角来自于一个正交脱酶结构模型，该模型先前确定为2.4 . ang。决议。利用RING程序系统，在Vector General 3400显示系统上建立了当前全酶分子的模型。该模型的结晶学r值为37.9%。在这两种形式的蛋白质分子之间存在着广泛的构象差异。构象发生了7.5度的旋转。催化结构域相对于辅酶结合结构域。这种旋转的铰链区域在两个螺旋之间的疏水核心内定义。结构域的内部结构被保留，除了辅酶结合结构域中的一个小环的运动。区域之间的间隙被这种辅酶诱导的构象变化所封闭，使得活性位点更难从溶液中接近，因此更疏水。这两个晶体独立的亚基非常相似，并且在目前的误差范围内与辅酶和抑制剂结合相同。辅酶分子以延伸构象结合，其两端位于辅酶结合域中心皱褶片相对两侧的疏水缝隙中。在Asp223、Lys228和His51的核糖片段上有氢键和氧原子。焦磷酸基团与Arg47和Arg369的侧链接触。
The structure of a triclinic complex between liver alcohol dehydrogenase, reduced coenzyme NADH and the inhibitor dimethylsulfoxide was determined to 2.9 .ANG. resolution using isomorphous replacement methods. The heavy-atom positions were derived by molecular replacement methods using phase angles derived from a model of the orthorhombic apoenzyme structure previously determined to 2.4 .ANG. resolution. A model of the present holoenzyme molecule was built on a Vector General 3400 display system using the RING system of programs. This model gave a crystallographic R-value of 37.9%. There are extensive conformational differences between the protein molecules in the 2 forms. The conformational change involves a rotation of 7.5.degree. of the catalytic domains relative to the coenzyme binding domains. A hinge region for this rotation is defined within a hydrophobic core between 2 helices. The internal structures of the domains are preserved with the exception of a movement of a small loop in the coenzyme binding domain. A cleft between the domains is closed by this coenzyme-induced conformational change, making the active site less accessible from solution and thus more hydrophobic. The 2 crystallographically independent subunits are very similar and bind coenzyme and inhibitor identically within the present limits of error. The coenzyme molecule is bound in an extended conformation with the 2 ends in hydrophobic crevices on opposite sides of the central pleated sheet of the coenzyme binding domain. There are hydrogen bonds to oxygen atoms of the ribose moieties from Asp223, Lys228 and His51. The pyrophosphate group is in contact with the side-chains of Arg47 and Arg369.