STRUCTURE OF MYOHEMERYTHRIN IN THE AZIDOMET STATE AT 1.7/1.3-A RESOLUTION
STRUCTURE OF MYOHEMERYTHRIN IN THE AZIDOMET STATE AT 1.7/1.3-A RESOLUTION
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DOI：
10.1016/0022-2836(87)90124-0
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发表时间：
1987-09-20
影响因子：
5.6
通讯作者：
SMITH, JL
中科院分区：
文献类型：
--
作者：
SHERIFF, S;HENDRICKSON, WA;SMITH, JL
肌红蛋白是一种来自蠕虫的携氧蛋白质，其分子模型已通过在1.7/1.3埃处的立体化学限制最小二乘最小化进行了改进。分离度达到常规R值0.158。估计的位置标准偏差优于0.15埃。979个蛋白质原子中的大部分。蛋白质原子的平均各向同性位移参数B为23.1埃2。这种高平均B参数似乎是由于分子的整体运动，这与观察到的各向异性衍射相关。7个残基的侧链在两种构象中建模，即侧链是离散无序的，并且几个赖氨酸和谷氨酸侧链的B参数表明它们是不良本地化的。在肌红蛋白中的残基中，66%是螺旋形的，其中62%以四个长α-主链扭转角平均值为v φ的螺旋。=-65 °，. ψ。=-42 °，对于N的氢键距离O，3.0.而H... 0，2.1.埃，和N的角度。cxa.H.dbd.C，153 °，N.sbd.. cxa. H. O，157 °，还有H... cxa.O.dbd.C，147 ℃。对于三分之二的α-螺旋残基，C α的扭转旋转。sbd.C.beta.键，χ 1，约为-60 °，而对于三分之一χ 1约为180 °。虽然大多数转肌红蛋白是由以前的分类很好地分类，两个不适合在既定的模式。在改进模型中还包括三个硫酸根离子，全部被部分占据。只有一个水分子在蛋白质内部，其余的在表面上，主要在与水分子相关的分子之间观察到，沿着货车德瓦尔斯接触，分子之间的大部分相互作用。蛋白质分子间有八个氢键，其中只有四个位于位置良好的原子之间。
The molecular model of myohemerythrin, an oxygen-carrying protein from sipunculan worms, has been refined by stereochemically restrained least-squares minimization at 1.7/1.3 .ANG. resolution to a conventional R-value of 0.158. The estimated positional standard deviation is better than 0.15 .ANG. for most of the 979 protein atoms. The average isotropic displacement parameter, B, for the protein atoms is 23.1 .ANG.2. This high average B parameter appears to be due to the overall motion of the molecule, which correlates with the observed anisotropic diffraction. The side-chains of seven residues were modeled in two conformations, i.e. the side-chains were discretely disordered, and B parameters for several lysine and glutamate side-chains indicate that they are poorly localized. Of the residues in myohemerythrin, 66% are helical, with 62% occurring in four long .alpha.-helices with mean values for the backbone torsion angles of .vphi. = -65.degree., .psi. = -42.degree., and for the hydrogen bonds distances of N...O, 3.0 .ANG. and H...0, 2.1 .ANG., and angles of N....cxa.H.dbd.C, 153.degree., N.sbd..cxa.H...O, 157.degree., and H....cxa.O.dbd.C, 147.degree.. For two-thirds of the .alpha.-helical residues, the torsional rotation of the C.alpha..sbd.C.beta. bond, .chi.1, is approximately -60.degree., and for one-third .chi.1 is approximately 180.degree.. Although most turns in myohemerythrin are well-categorized by previous classification, two do not fit in established patterns. Also included in the refined model are three sulfate ions, all partially occupied. Only one water molecule is internal to the protein, the remainder occur on the surface and are observed principally between symmetry-related molecules contributing, along with van der Waals'' contacts, most of the interactions between molecules. There are eight intermolecular protein-protein hydrogen bonds, of which only four are between well-located atoms.