Abstract
In the removal of phenolic precipitates formed by horseradish peroxidase (HRP) and $H_2O_2$ from waste water, the effects of the concentrations of phenolic compounds and $H_2O_2$ on the removal efficiency of various phenols were studied. More than 90% of various phenolic compounds were removed from the aqueous solutions (pH 5-7) by HRP and H2O2. The removal efficiency of phenolic compounds by HRP was reduced to a great extent when the initial concentration of $H_2O_2$ was over 10mM. Furthermore, no phenolic compounds were removed when 50mM of $H_2O_2$ was used. The HRP's turnover number, which indicates the number of phenolic molecules removed per one molecule of HRP, was the largest as 18047 for p-ethoxyphenol while it was the smallest as 1244 for m-chlorophenol when the initial concentrations of phenolic compounds and H2O2 were the same at 1mM. HRP which was separated from the aqueous solution containing phenol and $H_2O_2$ after 24hr of reaction revealed structural changes and diminished activity. The Soret absorbance near 404nm of this HRP sample was decreased to 48% of that of fresh HRP. The values of kcat and kcat/Km of this HRP sample for the oxidation of guaiacol were also reduced to 41% and 51% of those of fresh HRP, respectively. The removals of nonphenolic aromatic compounds such as benzene, ethylbenzene, and toluene (BET) by HRP and $H_2O_2$ were enhanced when phenols were coexisting in the aqueous solutions of BET.
페놀이 포함되어 있는 수용액에 HRP 및 $H_2O_2$를 첨가하여 페놀을 침전 및 제거시키는 방법에서, 페 놀의 종류와 페놀 및 $H_2O_2$의 농도가 HRP의 페놀제거 효율에 미치는 영향을 조사하였다. 여러 가지 페 놀성분은 최척 완충용액 (pH 5~7) 에서 HRP와 $H_2O_2$를 사용해서 90% 이상 제거할 수 있었다. $H_2O_2$ 의 농도가 10mM 이상일 때 HRP의 페놀제거 효율 이 급격히 감소하였으며 HzOz의 농도가 50mM 이 상얼 때 HRP의 페놀제거 효율은 거의 없었다. HRP 한 분자당 제거할 수 있는 페놀의 분자수 (turnover number)는 $H_2O_2$ 빛 페놀물질의 초기농 도가 각각 ImM일 때, p-ethoxyphenol의 경우 18047로 가장 켰으며 m-chlorophenol의 경우 1244로서 가장 척였다. 페놀과 반응 후($25^{\circ}C$, 24h) 반응물질로부터 분리된 HRP의 Soret 파장 (404nm)에셔의 흡광도는 원래효소의 48%로 감소 하였고 kcat 및 kcatjKm값은 각각 원래효소의 41 %와 51 %로 감소함으로서 페놀 제거시 HRP의 구 조변화 및 활성저하가 초래되었음을 알 수 있었다. 페놀과 함께 비 페놀계 방향성 물질인 벤젠, 에틸벤 젠, 툴루엔 (BET)을 포함하고 있는 용액 에 HRP 빛 $H_2O_2$를 첨가하면 BET의 제거율이 증가하였다.