摘要
目的:通过测定并比较变形链球菌耐氟菌株及其亲代菌株体内质子移位膜ATP酶的活性,以阐明耐氟菌株耐酸能力提高的原因。方法:将变链菌株Ingbritt及其耐氟突变株Ingbritt-FR通过甲苯处理,2个循环的液氮冷冻和37℃解冻,制成透性细胞。将透性细胞悬液加到含有10mmol/LMgSO4的50mmol/LTris-maleate测试缓冲液中(pH6.0),加温至37℃,再加入5mmol/LATP(pH6.0)起动反应。分别于10、20、60min取样,测定样品中水解ATP所释出的无机磷量。采用磷钼酸比色法在紫外分光光度计上进行比色分析(660nm),所得数据采用双因素方差分析。结果:在10、20和60min时,耐氟菌株H+-ATP酶活性分别为308.48、136.67和82.80μmolPi/g细胞干重/min,显著高于亲代菌株的相应酶活性:104.77,、64.69和30.70(P<0.01)。随时间推移,两类菌株的H+-ATP酶活性均逐渐降低,在酶的作用时间差别上有统计学意义(P<0.01)。结论:耐氟菌株ATP酶活性增高为其耐酸性增高的原因;H+-ATP酶活性及耐酸性的增高将会增加变链菌耐氟菌株的致龋潜能。
PURPOSE: To figure out the reason for increased acid tolerance of Ingbritt-FR,the fluoride-resistant strain of Streptococcus mutans Ingbritt,by determining and comparing the H+-ATPase activities of both fluoride-resistant and their parental strains. METHODS: The permeabilized cells of S. mutans Ingbritt and Ingbritt-FR were prepared by treating them with 10% toluene and then two cycles of freezing and thawing. The permeabilized cells were used for ATPase assay by adding them to the reaction mixture which contained 50mM Tris-maleate buffer (pH 6.0),10mM MgSO4 and 5mM ATP. ATPase activity was assessed by measuring inorganic phosphate released from ATP hydrolysis.Two-way ANOVA was used for statistical analysis. RESULTS: The activities of H+-ATPase of Ingbritt-FR were 308.48,136.67,and 82.80 μmol Pi/g cell dry weight/min,at 10,20,and 60 minutes respectively,significantly higher than those of their parent strain:104.77,64.69,and 30.7 (P<0.01). The enzyme activities were decreasing with time. CONCLUSIONS: The higher ATPase activity of fluoride-resistant mutant of S. mutans Ingbritt may account for the increased acid tolerance of this organism,and the increment of ATPase activity and acid tolerance of fluoride-resistant strain is likely to increase the cariogenic potential of S. mutans after fluoride-resistant mutation.
出处
《上海口腔医学》
CAS
CSCD
2005年第1期71-73,共3页
Shanghai Journal of Stomatology
基金
国家自然科学基金(39870780)
