漆酶和氧合血蓝蛋白的磁化率研究。
Magnetic susceptibility studies of laccase and oxyhemocyanin.
作者信息
Dooley D M, Scott R A, Ellinghaus J, Solomon E I, Gray H B
出版信息
Proc Natl Acad Sci U S A. 1978 Jul;75(7):3019-22. doi: 10.1073/pnas.75.7.3019.
The magnetic susceptibility of Rhus vernicifera laccase has been remeasured over the temperature range 5-260 K. In contrast to our previous results [Solomon, E.I., Dooley, D. M., Wang R.-H., Gray, H.B., Cerdonio, M., Mogno, F. & Romani, G. L. (1975) J. Am. Chem. Soc. 98, 1029-1031] linear chi versus T-1 behavior was observed. The susceptibility of Limulus polyphemus oxyhemocyanin has also been measured in the range 5-260 K. Only weak paramagnetism, attributable to dissolved oxygen and a small amount of paramagnetic impurities, was observed. Analysis of the data establishes a lower limit of 550 cm-1 for J, consistent with our earlier work. The temperature dependence of the susceptibility of laccase is quantitatively accounted for by the presence of two paramagnetic copper ions (types 1 and 2) per enzyme molecule. Curie law behavior at low temperatures rules out significant interaction between the two coppper types, indicating that these redox centers are well separated (several angstroms) and are not connected by bridging ligands. Formulation of the type 3 site as binuclear Cu(II) requires J greater than or equal to 500 cm-1.
在5 - 260 K的温度范围内，对漆树漆酶的磁化率进行了重新测量。与我们之前的结果[所罗门，E.I.，杜利，D.M.，王R.-H.，格雷，H.B.，塞尔多尼奥，M.，莫尼奥，F. & 罗曼尼，G.L.（1975年）《美国化学会志》98，1029 - 1031]相反，观察到χ与T⁻¹呈线性关系。在5 - 260 K的范围内，也对鲎血蓝蛋白的磁化率进行了测量。仅观察到归因于溶解氧和少量顺磁性杂质的微弱顺磁性。对数据的分析确定J的下限为550 cm⁻¹，这与我们早期的工作一致。漆酶磁化率的温度依赖性由每个酶分子中存在两个顺磁性铜离子（1型和2型）定量解释。低温下的居里定律行为排除了两种铜离子之间的显著相互作用，表明这些氧化还原中心相距较远（几埃），且没有通过桥连配体相连。将3型位点表述为双核Cu(II)需要J≥500 cm⁻¹。
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