La Mar Gerd N
Department of Chemistry, University of California, Davis, California 95616, USA.
IUBMB Life. 2007 Aug-Sep;59(8-9):513-27. doi: 10.1080/15216540701194121.
The principles for the application of the paramagnetic dipolar field of low-spin, cyanide-inhibited ferrihemoproteins for determining active site structure are briefly described. The ubiquitous dipolar shifts for assigned residues, together with crystal coordinates of some appropriate structural homolog, allow determination of the orientation and anisotropies of the paramagnetic dipolar tensor. The orientation of chi uniquely defines the orientation of the Fe-CN unit, which is tilted variably and sensitively monitors distal steric and H-bond interactions. The mapped dipolar field, in turn, can be used to determine the orientation of mutated residues. Case studies involving unusual genetic variants and point mutants of myoglobins, human hemoglobins, horseradish peroxidase and its substrate complex of heme oxygenase are presented as examples.
简要描述了应用低自旋、氰化物抑制的高铁血红蛋白的顺磁偶极场来确定活性位点结构的原理。指定残基普遍存在的偶极位移，以及一些合适的结构同源物的晶体坐标，使得能够确定顺磁偶极张量的方向和各向异性。χ的方向唯一地定义了Fe-CN单元的方向，该单元可变倾斜，并灵敏地监测远端空间位阻和氢键相互作用。反过来，映射的偶极场可用于确定突变残基的方向。文中给出了涉及肌红蛋白、人血红蛋白、辣根过氧化物酶及其血红素加氧酶底物复合物的异常遗传变体和点突变体的案例研究作为示例。
