Park H W, Sancar A, Deisenhofer J
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235.
J Mol Biol. 1993 Jun 20;231(4):1122-5. doi: 10.1006/jmbi.1993.1356.
DNA photolyase from Escherichia coli (M(r) 54,000) consists of a polypeptide chain of 471 amino acids and the non-covalently bound cofactors methenyltetrahydrofolate (MTHF) and flavin adenine dinucleotide (FADH2). Two crystal forms of the enzyme were obtained; both have symmetry of space group P1. Form I has the unit cell dimensions a = 89.4 A, b = 97.3 A, c = 62.1 A, alpha = 108.3 degrees, beta = 97.4 degrees and gamma = 90.0 degrees. Diffraction from this form extends beyond 3 A resolution, but the crystals are radiation-sensitive and difficult to reproduce. Form II has the unit cell dimensions a = 62.6 A, b = 72.2 A, c = 58.5 A, alpha = 99.1 degrees, beta = 101.5 degrees and gamma = 72.0 degrees; most likely, the unit cell contains two molecules. High diffraction quality and reproducibility make form II suitable for structure analysis.
来自大肠杆菌的DNA光解酶（相对分子质量54,000）由一条含471个氨基酸的多肽链以及非共价结合的辅因子亚甲基四氢叶酸（MTHF）和黄素腺嘌呤二核苷酸（FADH2）组成。获得了该酶的两种晶体形式；二者均具有P1空间群对称性。晶型I的晶胞参数为a = 89.4 Å，b = 97.3 Å，c = 62.1 Å，α = 108.3°，β = 97.4°，γ = 90.0°。该晶型的衍射分辨率超过3 Å，但晶体对辐射敏感且难以重复制备。晶型II的晶胞参数为a = 62.6 Å，b = 72.2 Å，c = 58.5 Å，α = 99.1°，β = 101.5°，γ = 72.0°；晶胞中很可能包含两个分子。高衍射质量和可重复性使得晶型II适用于结构分析。
