【摘要】 目的探讨纯化的人类胎盘碱性磷酸酶（ＰＬＡＰ）的部分性质，为其结构与功能的研究积累资料。②方法应用分光光度法观察了温度、酸碱度及抑制剂对酶活力的影响；同时对其紫外吸收光谱进行了测定。③结果在该实验条件下，酶的最适温度为６５℃，对热稳定，－２５℃冷冻后酶的活力明显下降；最适ｐＨ为１１．０，在ｐＨ７．０～１１．５之间稳定；以对硝基酚磷酸二钠为底物，其Ｋｍ值为０．２５ｍｍｏｌ／Ｌ；Ｌ－苯丙氨酸是ＰＬＡＰ的反竞争性抑制剂，其抑制常数为２．３５ｍｍｏｌ／Ｌ，而ＮａＨ２ＰＯ４是ＰＬＡＰ的竞争性抑制剂，其抑制常数为０．９９ｍｍｏｌ／Ｌ；酶蛋白的最大紫外吸收波长为２８０ｎｍ．④结论了解纯化ＰＬＡＰ的上述性质，有助于其结构与功能的研究。更多还原

【Abstract】 Objective\ To study some of the properties of purified human placental alkaline phosphatase (PLAP). Methods\ The effects of temperature, pH and inhibitors on PLAP activity were studied by spectrophotometry and the ultraviolet absorption spectra of PLAP were simultaneously measured.\ Results\ The optimum temperature of PLAP was 65℃. PLAP was stable to heat and its activity markedly decreased when PLAP was frozen in -25℃. The optimum pH of PLAP was 11.0 and PLAP was stable in 7.0<pH<11.5 various solutions.The Km was 0.25mmol/L for p nitrophenylphosphate (PNPP). The Ki was 2.35mmol/L in the presence of 1mmol/L L phenylalanine and 0.99mmol/L in the presence of 1mmol/L NaH 2PO 4 with the double reciprocal plot. L phenylalanine was an uncompetitive inhibitor whereas NaH 2PO 4 was a competitive inhibitor for PLAP. The purified PLAP exhibits a unique ultraviolet absorption spectrum with a maximum at 280nm.\ Conclusion\ Understanding the above properties of PLAP may help to study its structure and functions更多还原