Desideri A, Paci M, Rotilio G
Department of Biology Tor Vergata University of Rome, Italy.
J Inorg Biochem. 1988 Jun;33(2):91-7. doi: 10.1016/0162-0134(88)80037-0.
Anions that do not coordinate to the catalytically active copper ion of Cu,Zn superoxide dismutase, but still affect the activity of the enzyme by weaker interactions with the protein moiety surrounding the active site (low affinity anions), uniformly perturbed the 1H NMR line of the NH group of the copper ligand His 46. This effect was detected on the enzyme having Co(II) substituted for the native Zn(II), in which the resonances of residues bound to the copper are detected because of the antiferromagnetic coupling between Cu(II) and Co(II). The interaction with the enzyme of phosphate, a good representative of low-affinity anions, was also studied by 31P NMR of the native enzyme and of enzyme samples covalently modified at all lysines or at the Arg 141, which is 5 A away from the copper. The results obtained indicate that Arg 141 is a likely candidate for binding of low-affinity anions in the vicinity of the copper and that the 1H NMR line of His 46 NH is diagnostic for such an interaction.
那些不与铜锌超氧化物歧化酶的催化活性铜离子配位，但仍通过与活性位点周围蛋白质部分的较弱相互作用影响酶活性的阴离子（低亲和力阴离子），均一地扰动了铜配体组氨酸46的NH基团的1H NMR谱线。在将钴（II）取代天然锌（II）的酶上检测到了这种效应，由于铜（II）和钴（II）之间的反铁磁耦合，可以检测到与铜结合的残基的共振。还通过天然酶以及在所有赖氨酸或距铜5埃的精氨酸141处共价修饰的酶样品的31P NMR研究了低亲和力阴离子的良好代表磷酸盐与酶的相互作用。获得的结果表明，精氨酸141可能是在铜附近结合低亲和力阴离子的候选者，并且组氨酸46 NH的1H NMR谱线可诊断这种相互作用。
