Streptomyces alboniger Hesseltin이 생산(生産)하는 단백질(蛋白質) 가수분해(加水分解) 효소(酵素)의 몇가지 이화학적(理化學的) 성질(性質)을 구명(究明)하여 본 결과(結果), 다음과 같다. 본(本) 효소(酵素)의 작용(作用) 최적(最適) pH와 작용(作用) 최적(最適) 온도(溫度)는 각각 pH 9.0과 $40^{circ}C$ 부근이었다. 본(本) 효소(酵素)의 안정(安定) pH 범위는 pH $6.0{sim}10.8$ 부근이었으며, 열처리(熱處理)에 대하여 $40^{circ}C$ 이하(以下)에서 안정(安定)하였으나 $70^{circ}C$에서는 10분(分) 처리(處理)로 처음 효소(酵素) 활성(活性)의 70%가 감소하였다. 본(本) 효소(酵素)는 Hammarsten casein과 cytocrom C에 대한 Km치(値)가 각각 $7.1{mu}M$과 $333.3{mu}M$이었다. 효소(酵素)의 활성(活性)은 금속(金屬) 이온에 대하여 $Fe^{+++}>Hg^{++}>Cu^{++}>Pb^{++}>Zn^{++}$의 순서로 저해(沮害)되었고 $Ca^{++}$ 에 의하여 효소(酵素) 활성(活性)이 증가된 반면, $Mg^{++}$과 $Co^{++}$에 의해서는 별 다른 영향(影響)을 받지 않았다. 또한 효소(酵素)는 EDTA에 의하여 강하게 저해(沮害)되었으며, EDTA에 의해 변성된 효소(酵素)에 $Ca^{++}$을 첨가할 경우 효소(酵素) 활성(活性)이 부활(復活)되었다.
Some physico-chemical properties of proteolytic enzyme produced from Streptomyces alboniger Hesseltine were characterized. The optimal pH and temperature of the enzyme were around pH 9.0 and $40^{circ}C$, respectively. The enzyme was stable between pH $6.0{sim}10.8$ and the enzyme activity was not inactivated by heat treatment in lower temperature than $40^{circ}C$. However the enzyme activity decreased by 70% of the initial activity for 10minutes at $70^{circ}C$. The Km value was $7.1{mu}M$ with Hammarsten casein and $333.3{mu}M$ with cytochrom C. The activity of enzyme was inhibited by metal ions in the order of $Fe^{+++}>Hg^{++}>Cu^{++}>Pb^{++}>Zn^{++}$, whereas $Ca^{++}$ increased the enzyme activity. There was no effect of $Mg^{++}$ and $Co^{++}$ on the enzyme activity. The enzyme was inhibited by EDTA strongly. When $Ca^{++}$ was added to the EDTA-denaturated enzyme, the activity of enzyme was restored.
