Müller-Enoch D, Gruler H
Z Naturforsch C J Biosci. 1986 May-Jun;41(5-6):604-12.
The cytochrome P-450 dependent monooxygenase system of rat liver microsomes is investigated by light dosimetry (action spectroscopy). The scoparone-O-demethylation activity is enhanced by light and depends on the wavelength of the irradiating light. The relative increase of the activity (about 15%) by the irradiating light (approximately 0.5 mW/cm2) is maximal at a wavelength of 400 nm. The light induced enhancement of the 7-ethoxycoumarin-O-deethylase activity was measured in reconstituted systems, consisting of one of two P-450 enzymes (P-450 beta NF-B and P-450 PB-B) with the NADPH-cytochrome P-450 reductase. The action spectrum of the reconstituted P-450 beta NF-B:NADPH-P-450 reductase complex shows a maximum between 420 and 440 nm. The relative increase of the activity induced by light of 420 nm was 7.3% and 9% for the reconstituted systems of P-450 beta NF-B and P-450 PB-B, respectively. The results are discussed in analogy to the classic experiments of Warburg with its blocked CO-enzyme-complex. The results can best be explained by the assumption that the light induced enhancement of the enzyme activity is due to an excitement of those intermediate states of the P-450 catalytic cycle (ferric and ferrous state of the heme iron) which are rate limiting.
通过光剂量测定法（作用光谱法）研究了大鼠肝微粒体的细胞色素P-450依赖性单加氧酶系统。滨蒿内酯-O-脱甲基酶活性受光增强，且取决于照射光的波长。照射光（约0.5 mW/cm²）引起的活性相对增加（约15%）在波长400 nm时最大。在由两种P-450酶（P-450βNF-B和P-450 PB-B）之一与NADPH-细胞色素P-450还原酶组成的重组系统中，测定了光诱导的7-乙氧基香豆素-O-脱乙基酶活性增强情况。重组的P-450βNF-B:NADPH-P-450还原酶复合物的作用光谱在420至440 nm之间出现最大值。对于P-450βNF-B和P-450 PB-B的重组系统，420 nm光诱导的活性相对增加分别为7.3%和9%。结合Warburg的经典实验及其受阻的一氧化碳-酶复合物对结果进行了讨论。这些结果最好通过假设光诱导的酶活性增强是由于P-450催化循环的那些限速中间状态（血红素铁的三价铁和二价铁状态）的激发来解释。
