Neeli Rajasekhar, Girvan Hazel M, Lawrence Andrew, Warren Martin J, Leys David, Scrutton Nigel S, Munro Andrew W
Manchester Interdisciplinary Biocentre, School of Chemical Engineering and Analytical Science, The University of Manchester, Jackson's Mill, UK.
FEBS Lett. 2005 Oct 24;579(25):5582-8. doi: 10.1016/j.febslet.2005.09.023. Epub 2005 Sep 28.
In the model P450 BM3 system, the P450 is fused to its diflavin reductase partner in a single polypeptide. BM3 dimerizes in solution, but the catalytic relevance of the phenomenon was hitherto unknown. We show that BM3 fatty acid hydroxylase specific activity decreases sharply at low enzyme concentrations, consistent with separation of active dimer into inactive monomer. Reductase-dependent specific activities are maintained or enhanced at low concentration, suggesting inter-flavin electron transfer is unaffected. Fatty acid oxidation is reconstituted by mixing inactive oxygenase (A264H) and FMN-depleted (G570D) mutants, demonstrating that inter-monomer (FMN(1)-to-heme(2)) electron transfer supports oxygenase activity in the BM3 dimer.
在细胞色素P450 BM3系统模型中，细胞色素P450与其双黄素还原酶伴侣融合在一条单一多肽链中。BM3在溶液中会形成二聚体，但迄今为止该现象的催化相关性尚不清楚。我们发现，在低酶浓度下，BM3脂肪酸羟化酶的比活性急剧下降，这与活性二聚体分离为无活性单体的情况一致。在低浓度下，依赖还原酶的比活性得以维持或增强，这表明黄素间的电子转移未受影响。通过混合无活性加氧酶（A264H）和耗尽FMN的（G570D）突变体可重建脂肪酸氧化，这表明单体间（FMN(1)到血红素(2)）的电子转移支持BM3二聚体中的加氧酶活性。
