Nagpal A, Chandra V, Kaur P, Singh T P
Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India.
Acta Crystallogr D Biol Crystallogr. 1999 Jun;55(Pt 6):1240-1. doi: 10.1107/s0907444999004783.
A novel complex of phospholipase A2 complexed with another venom protein has been isolated and purified from saw-scaled viper (Echis carinatus) venom. The molecular weights of the two components are 16 and 14 kDa, respectively. The complex was purified using an Affigel blue column and an anion-exchange (DEAE Sephacel) column. Long diamond-shaped crystals were obtained by hanging-drop vapour diffusion. The protein complex was dissolved at a concentration of 10 mg ml-1 in 20 mM sodium cacodylate, 1 mM CaCl2 and 2% dioxane at pH 6.0. The reservoir contained the same buffer with 7%(w/v) PEG 4000. Crystals appeared within 2-3 weeks. Native data to 2.9 A resolution have been obtained at 291 K. The crystals belong to the monoclinic space group P21 with unit-cell parameters a = 74.47, b = 47.87, c = 106.39 A, beta = 104.5 degrees and contain two molecules per asymmetric unit. Structure determination by molecular replacement is in progress.
从锯鳞蝰蛇（Echis carinatus）毒液中分离并纯化出一种与另一种毒液蛋白复合的新型磷脂酶A2复合物。这两种成分的分子量分别为16 kDa和14 kDa。该复合物通过Affigel蓝柱和阴离子交换（DEAE Sephacel）柱进行纯化。通过悬滴气相扩散法获得了长菱形晶体。将蛋白质复合物以10 mg/ml的浓度溶解在pH 6.0的20 mM二甲胂酸钠、1 mM氯化钙和2%二氧六环中。储液池含有相同的缓冲液以及7%（w/v）的聚乙二醇4000。晶体在2至3周内出现。在291 K下获得了分辨率为2.9 Å的原生数据。晶体属于单斜空间群P21，晶胞参数为a = 74.47、b = 47.87、c = 106.39 Å，β = 104.5°，每个不对称单元包含两个分子。分子置换法的结构测定正在进行中。
