不同pH及封闭氨基端对甘氨酸拮抗内毒素作用的影响

Influence of different pH and sealing of its amino terminal on the anti-endotoxin effect of glycine

目的和方法：用封闭群新西兰家兔５６只，分为７组，注射不同ｐＨ（４０，６０，７４，１００）的甘氨酸和内毒素混合液，观察注射后体温变化，由此反映出不同ｐＨ对甘氨酸拮抗内毒素致热作用的影响。结果：甘氨酸的拮抗效果在碱性溶液中减弱、酸性溶液中增强，这种变化与ｐＨ对甘氨酸ＮＨ＋３端解离程度的影响是一致的。进一步用氯甲酸苄脂封闭甘氨酸的氨基端，通过鲎试验方法观察到，封闭氨基端后甘氨酸对内毒素的拮抗作用消失。结论：甘氨酸拮抗内毒素的机制可能是通过其带正电荷的ＮＨ＋３端实现的，ＮＨ＋３与内毒素脂质Ａ上的ＰＯ４结合，干扰了内毒素的正常结构。

AIM and METHODS: Fifty-six healthy New Zealand rabbits were randomly divided into 7 groups. The body temperature changes of rabbits were observed after intravenous injection of mixed solution of glycine-endotoxinwith different pH values (4 0、6 0、7 4、10 0). RESULTS:The effect of glycine on endotoxin was decreased in basic solution and increased in acidic solution, which was in accordance with the effect of pH on the dissociation of glycine amino terminal (NH + 3). Furthermore, using TAL test method, it was found that the anti-endotoxin effect of glycine disappeared after sealing of its amino terminal.CONCLUSION:The mechanism of antagonism of glycine against endotoxin may be attributed to its positive amino terminal which may combine with the PO 4 group of lipid A of endotoxin and interfere with structural integrity of endotoxin.