Pseudomonas carboxydovorans의 세포내 단백질 가수분해 효소의 정제 및 특징

Purification and Some Properties of an Intracellular Protease from Pseudomonas Carboxydovorans

Azocasein을 기질로 사용하여 nutrient broth에서 성장한 Pseudomonas carboxydovorans로부터 다섯 단계의 순화 과정을 거쳐 68배 순화된 세포내 가용성 단백질 가수 분해 효소를 얻었다. Pyruvate나 succinate, acetate, 또는 일산화탄소를 이용하여 성장한 세균들은 이 효소의 활성을 나타내지 않았다. 순화된 효소의 크기는 약 53,000이었고, 한개의 polypeptide로 구성되어 있었다. 이 효소는 serinerp통의 단백질 가수분해 효소로 $Cd^{2+}, Cu^{2+}, Hg^{2+}$, 등의 2가 양이온과 EGTA에 의해 활성이 완전히 억제되었고 iodoacetamide에 의해 활성이 증가되었다. 이 효소는 pH 8.0과 $50^{\circ}C$에서 최대 활성을 나타내었으며, 일산화탄소 산화효소를 가수분해 시키지 못하였다.

A soluble intracellular protease from cells of Pseudomonas carboxydovorans, a carboxydobacterium, grown on nutrient broth was purified 68-fold in five steps to better than 95% homogeneity with a yield of 2.4% using azocasein as a substrate. The enzyme activity was not detected from cells grown on pyruvate, succinate, acetate, or CO as a sole source of carbon and energy. The molecular weight of the native enzyme was determined to be 53,000. Sodium dodecyl sulfate-gel electrophoresis revealed the purified enzyme a monomer. The enzyme was found to be a serine-type protease. The enzyme activity was inhibited completely by several divalent cations such as $Cd^{2+}, Cu^{2+}, Hg^{2+}$, and $Fe^{2+}$. The enzyme was also inhibited by EGTA, but was stimulated by iodoacetamide. The optimal pH and temperature for the enzyme reaction were found to be 8.0 and $50^{\circ}C$, respectively. The enzyme was inactive on CO dehydrogenase.