酵母羧甲基甘油醛-3-磷酸脱氢酶光照形成NAD荧光衍生物时的协同作用

• 作 者: 徐功巧 邹承鲁
• 机 构: 中国科学院生物物理研究所,中国科学院生物物理研究所 北京,北京
• 出 处: 中国科学(B辑 化学 生物学 农学 医学 地学)
• 发表日期: 1983年12期
• 关键词: 酵母 羧甲基 NAD 磷酸脱氢酶 荧光 光照 甘油醛 协同性 正协同性 天然酶

本文表明与兔肌酶相同,活性部位巯基羧甲基化的酵母甘油醛-3-磷酸脱氢酶在NAD+存在下,经紫外光照,形成一发射峰为410毫微米的荧光衍生物。对于在四个活性部位中只有两个被引入羰甲基的酵母酶,也得到同样的结果。用蛋白内禀荧光淬灭方法测定这两种羧甲基酶,结合NAD~+均为极微弱的负协同性,或几乎无协同性;但根据荧光衍生物形成的测定,两者却均为正协同性,这可能是由于NAD~+和酶朊的结合方位在含荧光衍生物的酶中与天然酶中较为接近所致。

This paper shows that, as with rabbit muscle enzymes, the active site, mercaptocarboxymethylated yeast glyceraldehyde-3-phosphate dehydrogenase, is irradiated with UV light in the presence of NAD + to form a fluorescent derivative with an emission peak of 410 nm. The same result was also obtained for yeast enzymes in which only two carbonyl groups were introduced in the four active sites. Both carboxymethyl enzymes were assayed by protein intrinsic fluorescence quenching and showed very weak negative synergy with NAD ~ +, or little if any synergy; however, both were found to be Positive synergy, which may be due to the binding orientation of NAD ~ + and enzyme protein in the fluorescent derivative-containing enzyme is closer to the native enzyme.