Lipman R S, Bailey S W, Jarrett J T, Matthews R G, Jorns M S
Department of Biological Chemistry, Hahnemann University School of Medicine, Philadelphia, Pennsylvania 19102, USA.
Biochemistry. 1995 Sep 5;34(35):11217-20. doi: 10.1021/bi00035a030.
DNA photolyase from Escherichia coli contains folate ([6S]-5,10-CH(+)-H4Pte(Glu)n = 3-6) and reduced FAD. The folate chromophore acts as an antenna, harvesting light energy which is transferred to the reduced flavin where DNA repair occurs. The folate binding stereospecificity of the enzyme was investigated by reconstituting the apoenzyme with [6R,S]-5,10-CH(+)-H4folate and reduced FAD. The isomer composition of [methyl-3H]-5-CH3-H4folate, released into solution upon reduction of the reconstituted enzyme with [3H]NaBH4, was analyzed by enzymatic and chiral chromatographic methods. Both methods showed that the reconstituted enzyme contained nearly equimolar amounts of [6R]- and [6S]-5,10-CH(+)-H4folate.
来自大肠杆菌的DNA光解酶含有叶酸（[6S]-5,10-CH(+)-H4Pte(Glu)n = 3 - 6）和还原型黄素腺嘌呤二核苷酸（FAD）。叶酸发色团充当天线，收集光能并将其转移到发生DNA修复的还原型黄素上。通过用[6R,S]-5,10-CH(+)-H4叶酸和还原型FAD重组脱辅基酶，研究了该酶对叶酸的结合立体特异性。用[3H]硼氢化钠还原重组酶后释放到溶液中的[甲基-3H]-5-CH3-H4叶酸的异构体组成，通过酶法和手性色谱法进行了分析。两种方法均表明，重组酶含有几乎等摩尔量的[6R]-和[6S]-5,10-CH(+)-H4叶酸。
