尖吻蝮蛇毒酸性磷脂酶A_2 的新晶型结构(英文)  

Structure of an Acidic Phospholipase A_2 from the Venom of Deinagkistrodon acutus in a New Crystal Form

作　　者：谷立川[1] 张海龙[1] 宋时英[1] 周元聪[2] 林政炯[1] 

机构地区：[1]中国科学院生物物理研究所生物大分子国家重点实验室,北京100101 [2]中国科学院生物化学与细胞生物学研究所,上海200031

出　　处：《生物化学与生物物理学报》2002年第3期266-272,共7页

基　　金：中国科学院科学基金资助 (No .39970 174)~~

摘　　要：从尖吻蝮蛇毒中分离出一种酸性磷脂酶A2 ,得到了一种新的晶型。用分子置换法测定其晶体结构 ,结构的分辨率达到 0 .2 8nm。该结构给出 2 1.9%的晶体学R因子 (R free =2 5 .7% )和合理的立体化学参数。与已报道的晶型相似 ,不对称单元的两个独立分子形成二体 ,揭示了这种二体的稳定性。二体的形成过程也伴随着 14～ 2 3肽段显著的构象变化 ,这一肽段属于磷脂酶A2 的界面识别部位。氨基酸序列分析表明 ,带正电荷的 34位残基是所有第二类具有溶血活性磷脂酶A2 的共同特点。NaCl对晶体的堆积具有显著的影响 ,从而导致晶胞参数的明显改变。与已报道的晶型不同 ,在酶分子的疏水通道内观测到了 2 甲基 2 ,4戊二醇 (2 methyl 2 ,4 pentanediol,MPD)The three-dimensional structure of an acidic phospholipase A 2 purified from the venom of Deinagkistrodon acutus (Agkistrodon acutus) was determined in a new crystal form by molecular replacement at 0.28 nm resolution with a crystallographic R factor of 21.9% (R-free=25.7%) and reasonable stereochemistry. Being similar to the previous reported crystal form, a significant conformational adaptation of segment 14—23 at the dimer interface was observed. This segment was related to the “interface recognition site” (IRS). It was found that a positively charged residue at position 34 seems to be a common feature for most of hemolytic PLA 2s belonging to group II. Structural comparison between the two crystal forms showed that NaCl had significant effects on the crystal packing, thus leading to dramatic changes of the unit cell parameters. In the new crystal form, MPD (2-methyl-2, 4-pentanediol) molecules exist in the hydrophobic channel of the enzyme.

关 键 词：尖吻蝮蛇毒 酸性磷脂酶A2 新晶型结构 X射线晶体学 三维结构 溶血活性 界面催化 

分 类 号：Q55[生物学—生物化学]