光敏反应对过氧化氢酶的影响

EFFECT OF PHOTOSENSITIVE REACTION ON CATALASE

光氧化反应中,纯过氧化氢酶活性受光敏化剂血卟啉Ⅳ和核黄素的抑制。随光敏化剂浓度增高及照光时间延长,抑制程度加大。酶与光敏化剂反应后吸收光谱位移,峰形改变。紫外差示吸收光谱出现229nm负峰(血卟啉)和236—240nm峰(核黄素)。结果表明酶活的抑制与其蛋白构象的变化相关。

Pure catalase from bovine liver was used to study the photosensitive effect by two photosensitizors hematoporphyrim and riboflavin. The change of enzyme protein conformation in solution was determinted by ultraviolet absorption difference spectra. The activity of catalase was measured by oxygen electrode.Catalase activity was inhibited in the presence of light and photosensitizor. The inhibition increased with the increasing concentration of photosensitizor and illumination time. Absorption spectra were shifted and the shape of absorption peak was modified in the catalase-photosensitizor reaction. A nagative peak of 229 nm and a 236—240 nm peak in UV difference spectra were observed by the action of hematoporphyrin and riboflavin, respectively.The results indicate that the activity inhibition of catalase induced by photosensitive oxidation was related to the change of enzyme protein conformation. It is suggested that the photosensitive inactivation of catalase may be due to the photodynamic injury caused by the active oxygen produced from photosensitive reaction.