Bicknell R, Hanson G R, Holmquist B, Little C
Biochemistry. 1986 Jul 29;25(15):4219-23. doi: 10.1021/bi00363a008.
The coordination sphere of both the structural and catalytic zinc ions of Bacillus cereus phospholipase C has been probed by substitution of cobalt(II) for zinc and investigation of the resultant derivatives by a variety of spectroscopic techniques. The electronic absorption, circular dichroic, magnetic circular dichroic, and electron paramagnetic resonance spectra were found to be strikingly similar when cobalt(II) was substituted into either site and are consistent with a distorted octahedral environment for the metal ion in both sites. Octahedral coordination appears comparatively rare in zinc metalloenzymes but has been suggested for glyoxalase I [Sellin, S., Eriksson, L. E. G., Aronsson, A.-C., & Mannervik, B. (1983) J. Biol. Chem. 258, 2091-2093; Garcia-Iniguez, L., Powers, L., Chance, B., Sellin, S., Mannervik, B., & Mildvan, A. S. (1984) Biochemistry 23, 685-689], transcarboxylase [Fung, C.-H., Mildvan, A. S., & Leigh, J. S. (1974) Biochemistry 13, 1160-1169], and the regulatory binding site of Aeromonas aminopeptidase [Prescott, J. M., Wagner, F. W., Holmquist, B., & Vallee, B. L. (1985) Biochemistry 24, 5350-5356]. Phospholipase C is so far unique in having two such sites.
通过用钴（II）取代锌，并使用多种光谱技术研究所得衍生物，对蜡样芽孢杆菌磷脂酶C的结构锌离子和催化锌离子的配位球进行了探测。当钴（II）被取代到任一位置时，发现电子吸收光谱、圆二色光谱、磁圆二色光谱和电子顺磁共振光谱非常相似，这与两个位置上金属离子的扭曲八面体环境一致。八面体配位在锌金属酶中似乎相对罕见，但已有人提出乙二醛酶I [Sellin, S., Eriksson, L. E. G., Aronsson, A.-C., & Mannervik, B. (1983) J. Biol. Chem. 258, 2091-2093; Garcia-Iniguez, L., Powers, L., Chance, B., Sellin, S., Mannervik, B., & Mildvan, A. S. (1984) Biochemistry 23, 685-689]、转羧酶 [Fung, C.-H., Mildvan, A. S., & Leigh, J. S. (1974) Biochemistry 13, 1160-1169] 以及气单胞菌氨肽酶的调节结合位点 [Prescott, J. M., Wagner, F. W., Holmquist, B., & Vallee, B. L. (1985) Biochemistry 24, 5350-5356] 具有这种配位方式。到目前为止，磷脂酶C在拥有两个这样的位点方面是独一无二的。
