Groeneveld C M, Aasa R, Reinhammar B, Canters G W
Gorlaeus Laboratories, Leiden University, The Netherlands.
J Inorg Biochem. 1987 Oct;31(2):143-54. doi: 10.1016/0162-0134(87)80059-4.
The X- and Q-band EPR spectra of Pseudomonas aeruginosa (63Cu)azurin and Alcaligenes denitrificans azurin have been measured at pH = 5.2 and 9.2, in the presence and absence of 40% glycerol. The EPR spectra of both proteins could properly be simulated by taking into account a spread in the tetrahedral angle of the copper site. The change in the EPR spectrum of Pseudomonas aeruginosa (63Cu)azurin that is observed upon an increase of the pH from 5.2 to 9.2 is consistent with a small decrease of the average tetrahedral angle from 61 degrees to 60 degrees. This geometrical change is consistent with the interpretation of earlier NMR and EXAFS observations. No pH effect is observed for Alcaligenes denitrificans azurin, in agreement with predictions based on crystallographic evidence. Glycerol has only a marginal effect on the appearance of the EPR spectra, and does not alleviate the "g-strain."
在pH = 5.2和9.2条件下，有和没有40%甘油存在时，测量了铜绿假单胞菌（63Cu）天青蛋白和反硝化产碱菌天青蛋白的X波段和Q波段电子顺磁共振（EPR）光谱。通过考虑铜位点四面体角的展宽，可以恰当地模拟这两种蛋白质的EPR光谱。当pH从5.2增加到9.2时，观察到铜绿假单胞菌（63Cu）天青蛋白的EPR光谱变化，这与平均四面体角从61度略微减小到60度一致。这种几何变化与早期核磁共振（NMR）和扩展X射线吸收精细结构（EXAFS）观察结果的解释一致。反硝化产碱菌天青蛋白未观察到pH效应，这与基于晶体学证据的预测一致。甘油对EPR光谱的外观只有轻微影响，并且不能减轻“g应变”。
