Sekar K, Vaijayanthi Mala S, Yogavel M, Velmurugan D, Poi Ming-Jye, Vishwanath B S, Gowda T V, Jeyaprakash A Arokia, Tsai M-D
Bioinformatics Centre, Indian Institute of Science, Bangalore 560 012, India.
J Mol Biol. 2003 Oct 17;333(2):367-76. doi: 10.1016/j.jmb.2003.08.032.
Phospholipase A2 catalyses the hydrolysis of the ester bond of 3-sn-phosphoglycerides. Here, we report the crystal structures of the free and anisic acid-bound triple mutant (K53,56,120M) of bovine pancreatic phospholipase A2. In the bound triple mutant structure, the small organic molecule p-anisic acid is found in the active site, and one of the carboxylate oxygen atoms is coordinated to the functionally important primary calcium ion. The other carboxylate oxygen atom is hydrogen bonded to the phenolic hydroxyl group of Tyr69. In addition, the bound anisic acid molecule replaces one of the functionally important water molecules in the active site. The residues 60-70, which are in a loop (surface loop), are disordered in most of the bovine pancreatic phospholipase A2 structures. It is interesting to note that these residues are ordered in the bound triple mutant structure but are disordered in the free triple mutant structure. The organic crystallization ingredient 2-methyl-2,4-pentanediol is found near the active site of the free triple mutant structure. The overall tertiary folding and stereochemical parameters for the final models of the free and anisic acid-bound triple mutant are virtually identical.
磷脂酶A2催化3 - sn - 磷脂甘油酯酯键的水解。在此，我们报道了牛胰磷脂酶A2的游离型和对甲氧基苯甲酸结合型三重突变体（K53,56,120M）的晶体结构。在结合型三重突变体结构中，活性位点发现了小分子有机分子对甲氧基苯甲酸，其中一个羧酸根氧原子与功能上重要的初级钙离子配位。另一个羧酸根氧原子与Tyr69的酚羟基形成氢键。此外，结合的对甲氧基苯甲酸分子取代了活性位点中一个功能上重要的水分子。位于环（表面环）中的60 - 70位残基在大多数牛胰磷脂酶A2结构中是无序的。值得注意的是，这些残基在结合型三重突变体结构中是有序的，但在游离型三重突变体结构中是无序的。在游离型三重突变体结构的活性位点附近发现了有机结晶成分2 - 甲基 - 2,4 - 戊二醇。游离型和对甲氧基苯甲酸结合型三重突变体最终模型的整体三级折叠和立体化学参数几乎相同。
