乳過氧酵素系統(LPO system)是人體口腔中天生具有對抗微生物的保護系統。本實驗之目的在研究乳過氧酵素(LPO),硫氰酸鈉(NaSCN)及過氧化氫(H2O2)之濃度對乳過氧酵素系統可能的影響。突變形鏈球菌株先在血瓊膠培養基上生長,取其上數個菌落再種入TSYG培養液內,在攝氏37度下生長一夜,經離心收集的細菌置於恒溫(攝氏37度)滴定儀內測試其產酸速率。酸鹼值維持在7.0。反應液內包含320μg/ml細菌(S. mutans ),2 mM酸鹼緩衝液,18 mM KCL,0.4 mM MgCl2,20 mM葡萄糖與不同濃度之過氧化氫、硫氰酸鈉及乳過氧酵素。結果顯示當H2O2濃度增加時LPO及SCN^-濃度亦須增加才能達到抑制S. mutans產酸的效果。適當的H_2O_2濃度可抑制S. mutans產酸之效力,但過大H_2O_2濃度反而會減少抑制S. mutans產酸之效果。結論:LPO system所造成抑制S. mutans產酸速率的作用會受到個別因子的影響。
Lactoperoxidase (LPO) catalyzes the oxidation of thiocyanate (SCN^-) by hydrogen peroxide (H_2O_2) yielding the antimicrobial substance hypothiocyanite (OSCN^-). Sugar transport and metabolism of S. mutans are inhibited by the LPO system. This study examined the effect of LPO, SCN^-, and H_2O_2 concentration on inhibition of acid production by S. mutans 10449 fermenting glucose. Cells were grown anaerobically at 37℃ in TSYG broth overnight, harvested and examined in a pH state at pH 7.0 and 37℃. Reaction mixtures contained cells (ca. 320g/ml dry wt.), 2 mM KPi, 18 mM KCl, 0.4 mM MgCl2, 20 mM glucose. Results showed that increased H2O2 concentrations need more LPO and SCN^- concentration to inhibit acid production of S. mutans. In the same concentration of LPO and SCN^-, adequate H_2O_2 concentration could inhibit acid production of S. mutans but lower or more H_2O_2 concentrations reduced the inhibition effect. In conclusion, The effects of LPO system on the inhibition of acid production of S. mutans dependent on LPO, SCN^- and H_2O_2 concentrations.