钙离子对江浙蝮蛇蛇毒中性磷脂酶A2溶液构象的研究

用荧光光谱方法研究了钙离子对江浙蝮蛇毒中性磷脂酶Ａ２（简称ＮＰＬＡ２）构象的影响。结果表明，Ｃａ２＋能使酶中唯一的色氨酸残基的荧光增强：只有在Ｃａ２＋存在时，底物卵磷脂才明显改变酶分子中Ｔｒｐ周围的环境，使其光谱的兰移达７ｎｍ，荧光增强约一倍：酶中唯一的Ｈｉｓ残基被修饰以后，则没有上述两种现象发生；结合在ＮＰＬＡ２上的ｂｉｓＡＮＳ的荧光强度，随Ｃａ２＋浓度的增加而增强，提示Ｃａ２＋对ｂｉｓ－ＡＮＳ结合区域的构象有明显影响。

EFFECT OF CALCIUM ION ON THE CONFORMATION OF NETURAL PHOSPHOLIPASE A2 FROM THE VENOM OF AGKISTRODON HALYS PALLS

The effect of calcium ion on the conformation of neutral phospholipase A2(NPLA2) from the venom of Agkistrodon kalys palls was studied by fluorescence spectroscopy.The results indicated that calcium ion could cause an increase in the fluorescence intensity of the single Trp residue in NPLA2. only in the presence of calcium ion could the enzyme substrate lecithin cause an obvious change in the environment of Trp residue,leading to a 7 nm blue shift in the spectrum and double the fluorescence inthensity:no such phenomena was observed after the single His residue was modified.The fluorescence intensity of the bound bis-ANS to NPLA2 increased with the raising of the calcium concentration,which indicated that calcium ion would affect the conformation of bis-ANS binding area.