重组人血小板型磷脂酶A_2体外抗金黄色葡萄球菌的活性及其影响因素研究

Bactericidal Activity of Recombinant Human Platelet Phospholipase A_2 in Vitro Against Staphylococcus Aureus and Its Impact Factors

目的:体外评价具有强正电荷性的重组人血小板型磷脂酶A2(RHP-PLA2)对金黄色葡萄球菌的杀菌活性,观察其在不同影响因素及水平下杀菌活性的变化。方法:用琼脂平板计数法测定杀菌活性,并对影响其杀菌活性的pH、Ca2+、Mg2+、肝素(带负电荷)等因素及水平进行测定。结果:RHP-PLA2杀灭99%金黄色葡萄球菌的最低浓度(MBC)为0.08ng.L-1。在MBC时,当pH为5.0、7.4、9.0时,RHP-PLA2杀菌率分别为44.4%、99.8%、99.5%;1～5mmol·L-1Ca2+适于RHP-PLA2发挥杀菌活性;5.12mmol·L-1乙二醇二乙醚二胺四乙酸、10mmol·L-1MgCl2及0.30×10-4IU.L-1肝素可完全抑制RHP-PLA2杀菌作用。结论:RHP-PLA2杀菌活性受pH值和Ca2+浓度的影响。PLA2分子带的正电荷性是其发挥杀菌活性的关键因素。

OBJECTIVE： To evaluate the bactericidal activity of recombinant human platelet phospholipase A2 （RHP- PLA2） in vitro against S.aureus and the effects of different impact factors on the bactericidal activity of it. METHODS： The bactericidal activity of RHP- PLA2 was tested by agar plating method, and the impact factors （pH, Ca^2＋, Mg^2＋, negatively charged heparin） were determined. RESULTS： The minimum bactericidal concentration （MBC） of RHP-PLA2 killing 99% S.aureus was 0.08 ng · L ^-1. The bactericidal rates of PLA2 at MBC were 44.4%, 99.8% and 99.5% respectively in the pH of 5.0, 7.4 and 9.0. 1 -5 mmol Ca^2 ＋ was suitable for the bactericidal activity of the RHP- PLA2. The bactericidal activity of RHP- PLA2 can be completely inhibited by 5.12 mmol· L ^-1 EGTA, 10 mmol · L^-1 MgCl2 or 0.30× 10^- 4 IU · L^- 1 heparin. CONCLUSIONS： The bactericidal activity of RHP- PLA2 is affected by pH and Ca^2＋ concentration in media. The cationic property of PLA2 is the key factor influencing its bactericidal activity.