Santel H J, Apel K
Eur J Biochem. 1981 Nov;120(1):95-103. doi: 10.1111/j.1432-1033.1981.tb05674.x.
During the illumination of etiolated barley plants a rapid decline of the NADPH: protochlorophyllide oxidoreductase is observed. Within the first 5 min of continuous light approximately 90% of the enzyme activity present in dark-grown barley plants disappears and, at the same time, the amount of enzyme protein is diminished by more than 60%. No stable polypeptide fragments have been found which might be formed during the light-induced degradation of the enzyme protein. The rate of enzyme protein synthesis is not drastically affected at the beginning of the illumination period. During the subsequent light-dependent chloroplast development a phytochrome-induced decline in the rate of protein synthesis, concomittant with a continuous light-dependent degradation of the enzyme protein, leads to a progressive decrease of the concentration of the enzyme. After 6 h of continuous light, when the rate of chlorophyll accumulation is at its greatest, only traces of the enzyme protein are visible and the enzyme activity is no longer detectable within the plants. In contrast to previous concepts of chlorophyll biosynthesis in higher plants, our results present evidence that the NADPH: protochlorophyllide oxidoreductase functions only for a short time period after the onset of light.
在黄化大麦植株受光照期间，可观察到NADPH：原叶绿素酸酯氧化还原酶迅速下降。在持续光照的最初5分钟内，黑暗生长的大麦植株中约90%的酶活性消失，同时，酶蛋白量减少超过60%。未发现可能在光诱导的酶蛋白降解过程中形成的稳定多肽片段。在光照期开始时，酶蛋白的合成速率没有受到显著影响。在随后依赖光的叶绿体发育过程中，光敏色素诱导的蛋白质合成速率下降，同时伴随着酶蛋白持续的光依赖性降解，导致该酶浓度逐渐降低。连续光照6小时后，当叶绿素积累速率最大时，仅可见痕量的酶蛋白，且在植株内不再检测到酶活性。与高等植物叶绿素生物合成的先前概念相反，我们的结果表明，NADPH：原叶绿素酸酯氧化还原酶仅在光照开始后的短时间内起作用。
