摘要
本文用ESR方法研究了竹红菌甲素和半胱氨酸在光和暗条件下产生活性氧的过程.我们发现甲素具有氧化还原反应中间载体的作用,即巯基化合物将电子转移给甲素,而甲素在有氧的条件下再将电子转移给氧生成超氧阴离子自由基.光照可以加快这一步骤,使用化学方法定量研究证明激发态甲素与半胱氨酸的反应速率大于基态甲素.除半胱氨酸外,巯基乙醇和还原谷胱甘肽均可以将电子经甲素传给氧,而甲硫氨酸和胱氨酸不具这一能力,这说明巯基在反应中很重要而硫原子不是必需的.
The mechanisms of radical generation in the rection both HA and cysteine were investigated with ESR and chemical techniques in this paper. The evidences showed that HA acted as a mediator in the redox Cycling, i.e. electrons were transported from sulfhydrylcompounds to HA, and in turn, relayed to oxygen forming superoxide anion radical in dark. This process can be enhanced by illumination. We found Synevgic action were existed between reaction in dark and in light which strongly suggested that excited HA reacting with cysteine would be faster than that of HA in ground state. Besides cysteine, mercaptoethanol and reduced glutathione were also capable of denoting their electrons to oxygen mediated by HA, but it was failure in the case of cystine and methionine, which indicated that sulfhydryl groups were improtant in the reaction rather than sulfuric atoms.
出处
《生物物理学报》
CAS
CSCD
北大核心
1990年第4期466-471,共6页
Acta Biophysica Sinica
