전통 메주로부터 분리한 Bacillus subtilis PCA 20-3 유래의 Protease 생산과 특성

Characteristics of Protease Produced by Bacillus subtilis PCA 20-3 isolated from Korean Traditional Meju

한국 전통 메주로부터 분리 동정한 Bacillus subtilis PCA20-3이 생산하는 protease의 생산조건과 특성을 조사하였다. Protease의 생산 최적조건을 0.2% soytone, 2% starch, 0.1% $(NH_4)_2SO_4,\;0.2%\;CaCl_2,\;0.01%\;yeast\;extract,\;0.1%\;K_2HPO_4,\;0.1%\;KH_2PO_4$, pH 7.0, 30에서 20시간이었다. 효소의 최적작용 pH와 온도는 6.0-11.0, $55^{\circ}C$였고 pH $6.0{\sim}11.0$의 범위와 $50^{\circ}C$이하에서 안정하였다. 금속이온중 $Fe^{(2+)}$와 $Cu^{(2+)}$에 의해 효소활성이 저해되었다. 2mM의 phenymethanesulfonyl fluoride에 의해 89.2%의 활성이 저하되어, 활성 serine을 가진 serine protease임이 시사되었다. 조효소액의 Km값은 $5.0{\times}10^{(-4)}M,\;V_(max)$값은 $100\;{\mu}g/min$이었으며 bovine serum albumin, isolated soybean protein 보다 casein에 대해 초기 가수분해력이 높은 것으로 나타났다.

Protease production and its characteristics were investigated with Bacillus subtilis PCA20-3 which was isolated from Korean traditional meju. The optimum culture conditions of Bacillus subtilis PCA20-3 for the production of the protease were as follow: 0.2% soytone, 2% starch, 0.1% $(NH_4)_2SO_4,\;0.2%\;CaCl_2,\;0.01%\;yeast\;extract,\;0.1%\; K_2HPO_4,\;0.1%\;KH_2PO_4,\;pH\;7.0,\;30^{\circ}C$ and 20 hrs. The optimum pH and temperature for enzyme activity of protease producing Bacillus subtilis PCA20-3 were pH 8.0-10.0 and $55^{\circ}C$, respectively. The enzyme was relatively stable at pH $6.0{\sim}11.0$ and at temperature below $50^{\circ}C$. The activity of the enzyme was inhibited by $Fe^(2＋)\;and\;Cu^(2＋)$. 2 mM phenymethanesulfonyl fluoride inhibited 89.2% of enzyme activity. This indicates that the enzyme is serine protease. The $K_m$ value was $5\;{\times}\;10^{-4}\;M,\;V_{max}\;value\;was\;100\;{\mu}g/min$. This enzyme hydrolyzed casein more rapidly than bovine serum albumin.