摘要
目的:初步探讨在牙菌斑生物膜天然环境中,内氏放线菌尿素酶能否发挥高效尿素水解反应,以及尿素水解对口腔环境中pH值的调节作用。方法:通过酶促反应动力学实验寻找内氏放线菌尿素水解的最适条件,监测尿素水解调节细菌产酸后的pH值变化。采用SPSS软件包,对酶促动力学实验数据进行线性回归与相关分析。结果:内氏放线菌尿素酶米氏常数Km=7.5mmol/L,在口腔中正常尿素浓度3～10mmol/L范围内,内氏放线菌尿素酶催化活性大约保持在最大活性的20%～63%;内氏放线菌尿素酶最适pH值=6.5,但是在牙菌斑临界pH5.0,尿素酶活性仍保持40%的最大活性;在口腔正常尿素浓度范围内,内氏放线菌尿素水解产物中和细菌产酸后,pH值不会下降到牙菌斑临界pH5.0以下。结论:在牙菌斑生物膜中,内氏放线菌尿素酶可以发挥高效尿素水解反应,尿素水解对口腔环境pH值具有明显的调节作用。
PURPOSE： To explore whether the ureolysis ofAetinomyees naeslundii could keep high level in the natural dental biofilm and the effect of ureolysis on the environmental pH balance preliminarily. METHODS： Enzyme kinetic test was used to detect the optimal condition for ureolysis; and the pH change was measured under ureolysis after acidgenesis. SPSS software package was used for linear regression and correlation analysis. RESULTS： The Km of urease was 7.5mmol/L,it could keep 20% to 63% of the optimal activity with the concentration of urea normally found in the mouth which was at the range of 3-10mmol/L;The optimal pH of ureolysis was 6.5, but at pH 5.0 which was the threshold pH of dental plaque, the enzyme had 40% of the optimal activity; with the concentration of urea normally found in the mouth, pH would not decrease to the threshold pH with ureolysis after acidification. CONCLUSION： In the dental plaque biofilm, A. naeslundii could ureolyze highly actively; ureolysis could moderate the pH balance of plaque significantly.
出处
《上海口腔医学》
CAS
CSCD
2005年第6期605-607,共3页
Shanghai Journal of Stomatology
基金
国家自然科学基金(30430800
30371541)
关键词
尿素酶
内氏放线菌
牙菌斑生物膜
酸碱平衡
Urease
Actinomyces naeslundii
Dental plaque biofilm
pH homeostasis
