Autoxidation of cysteine catalyzed by copper in glycylglycine buffer.
Autoxidation of cysteine catalyzed by copper in glycylglycine buffer.
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DOI：
10.1248/cpb.23.1671
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发表时间：
1975-08
影响因子：
1.7
通讯作者：
A. Hanaki;H. Kamide
中科院分区：
文献类型：
--
作者：
A. Hanaki;H. Kamide
用分光光度法研究了Cu （II）在甘氨酸缓冲液中催化半胱氨酸的自氧化作用。Cu （II）和半胱氨酸溶液混合后，由于Cu (II)-半胱氨酸络合物，产生了一种瞬态紫色，具有宽的电子光谱，λmax=530 nm。紫色Cu （II）配合物随着pH值的增加而相对稳定，其迅速分解为Cu (I)种。半胱氨酸的自氧化不表现出Michaelis-Menten动力学行为，并且在pH 7.3以上半胱氨酸浓度下表现为半阶自氧化。培养基中氧气浓度的增加促进了自氧化。当半胱氨酸被氧化时，会产生过氧化氢并部分积累。速率的倒数与氧浓度的倒数的关系图是一条直线。一摩尔氧可能参与了Cu (I)的再氧化的一个步骤。自氧化反应的pH-速率曲线呈钟形曲线，pH值为7.4时达到最大值。
Autoxidation of cysteine catalyzed by Cu (II) in glycylglycine buffer was examined spectrophotometrically. Upon mixing the Cu (II) and cysteine solutions was produced a transient purple color, due to a Cu (II)-cysteine complex, giving a broad electronic spectrum with λmax=530 nm. The purple Cu (II) complex, which is decomposed fleetingly to Cu (I) species, is stabilized relatively as pH increases. The autoxidation of cysteine does not exhibit Michaelis-Menten kinetic behaviors, and appears to be half order in concentration of cysteine over pH 7.3. Increasing concentrations of oxygen in the medium promote the autoxidation. As cysteine is autoxidized, hydrogen peroxide is produced and partially accumulated. The plot of the reciprocal of the rate as a function of the reciprocal of the oxygen concentration gives a straight line. One molar oxygen participates probably in a step of the reoxidation of the Cu (I) species. A pH-rate profile of the autoxidation displays a bell-shaped curve with a maximum at pH 7.4.