Moratal J M, Castells J, Donaire A, Salgado J, Jiménez H R, Domingo R
Department of Inorganic Chemistry, University of Valencia, Spain.
J Inorg Biochem. 1994 Jan;53(1):1-11. doi: 10.1016/0162-0134(94)80016-2.
The interaction of cobalt(II) with native and cobalt(II)-substituted carboxypeptidase has been investigated, at pH 7.5, by electronic absorption and 1H NMR spectroscopies. The reaction of the cobalt(II) uptake by the metalloenzyme [MCPA] (M = Zn or Co) occurs very slowly and a bimetallic complex, [MCPA(Co)], is formed. On the basis of the 1H NOE experiments, the isotropically shifted proton resonances were assigned as belonging to a coordinated histidine residue. 1H NMR titrations of [ZnCPA(Co)] with zinc(II) show that the zinc ion does not compete with cobalt for binding to the noncatalytic site. The temperature dependence of the isotropic shifts, molar absorbance, and longitudinal relaxation time values are indicative of a five-coordinated geometry for the cobalt ion. The identification of the noncatalytic cobalt binding site is also discussed.
在pH 7.5条件下，通过电子吸收光谱和1H NMR光谱研究了钴（II）与天然及钴（II）取代的羧肽酶之间的相互作用。金属酶[MCPA]（M = Zn或Co）摄取钴（II）的反应非常缓慢，会形成双金属配合物[MCPA(Co)]。基于1H NOE实验，各向同性位移的质子共振被指定为属于一个配位的组氨酸残基。用锌（II）对[ZnCPA(Co)]进行1H NMR滴定表明，锌离子不会与钴竞争结合非催化位点。各向同性位移、摩尔吸光度和纵向弛豫时间值的温度依赖性表明钴离子具有五配位几何结构。还讨论了非催化钴结合位点的鉴定。
