Joubert F J, Van der Walt S J
Biochim Biophys Acta. 1975 Feb 27;379(2):317-28. doi: 10.1016/0005-2795(75)90140-3.
Three phospholipases A (Fractions DE-I, DE-II and DE-III) were purified from Naja melanoleuca (Forest cobra) venom by a combination of gel filtration on Sephadex G-50 and chromatography on DEAE-cellulosemthe purified phospholipases A were homogeneous by various physicochemical criteria. Whereas Fraction DE-I contains 118 amino acid residues, Fractions DE-II and DE-III comprise 119 residues. The three enzymes are cross-linked by seven disulphide bridges, have asparagine as N-terminal amino acid and the C-terminal is glutamic acid or glutamine. The molecular weights of the three phospholipases A from sedimentation analysis at pH 2.1, also by the sodium dodecylsulphate-gel method and calculated from the amino acid composition, were close to 13 000. Studies of circular dichroism in the spectral region between 195 to 305 nm showed that the three phospholipases A contain similar helical contents but revealed conformational differences between their side-chain chromophores.
通过葡聚糖凝胶G - 50凝胶过滤和二乙氨基乙基纤维素色谱法相结合，从黑曼巴蛇（森林眼镜蛇）毒液中纯化出三种磷脂酶A（DE - I、DE - II和DE - III组分）；通过各种物理化学标准判断，纯化后的磷脂酶A是均一的。DE - I组分含有118个氨基酸残基，而DE - II和DE - III组分包含119个残基。这三种酶通过七个二硫键交联，N端氨基酸为天冬酰胺，C端为谷氨酸或谷氨酰胺。通过在pH 2.1条件下的沉降分析、十二烷基硫酸钠凝胶法以及根据氨基酸组成计算得出，这三种磷脂酶A的分子量接近13000。对195至305纳米光谱区域的圆二色性研究表明，这三种磷脂酶A含有相似的螺旋含量，但它们侧链发色团之间存在构象差异。
