Sekar K, Rajakannan V, Gayathri D, Velmurugan D, Poi M-J, Dauter M, Dauter Z, Tsai M-D
Bioinformatics Centre, Indian Institute of Science, Bangalore 560 012, India.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2005 Jan 1;61(Pt 1):3-7. doi: 10.1107/S1744309104021748. Epub 2004 Sep 25.
The enzyme phospholipase A2 catalyzes the hydrolysis of the sn-2 acyl chain of phospholipids, forming fatty acids and lysophospholipids. The crystal structure of a triple mutant (K53,56,121M) of bovine pancreatic phospholipase A2 in which the lysine residues at positions 53, 56 and 121 are replaced recombinantly by methionines has been determined at atomic resolution (0.97 A). The crystal is monoclinic (space group P2), with unit-cell parameters a = 36.934, b = 23.863, c = 65.931 A, beta = 101.47 degrees. The structure was solved by molecular replacement and has been refined to a final R factor of 10.6% (Rfree = 13.4%) using 63,926 unique reflections. The final protein model consists of 123 amino-acid residues, two calcium ions, one chloride ion, 243 water molecules and six 2-methyl-2,4-pentanediol molecules. The surface-loop residues 60-70 are ordered and have clear electron density.
磷脂酶A2催化磷脂sn-2酰基链的水解，生成脂肪酸和溶血磷脂。已确定牛胰磷脂酶A2的三重突变体（K53、56、121M）的晶体结构，其中53、56和121位的赖氨酸残基被蛋氨酸重组取代，分辨率达到原子水平（0.97 Å）。晶体为单斜晶系（空间群P2），晶胞参数a = 36.934、b = 23.863、c = 65.931 Å，β = 101.47°。通过分子置换法解析了该结构，并使用63,926个独立反射将其精修至最终R因子为10.6%（Rfree = 13.4%）。最终的蛋白质模型由123个氨基酸残基、两个钙离子、一个氯离子、243个水分子和六个2-甲基-2,4-戊二醇分子组成。表面环残基60 - 70有序排列且具有清晰的电子密度。
