한국산 대추의 Endo-Polygalacturonase의 특성

Characteristics of Endo-Polygalacturonase from Korean jujube

한국산 대추의 endo-polygalacturonase는 최대 효소활성을 위한 pH는 5.0, 최적온도는 $50^{\circ}C$였으며 pH안정범위는 $4.0{\sim}5.0$, 열안정성은 $70^{\circ}C$에서 1시간 열처리 하였을 때 약 35% 실활되었다. 금속이온중 $Cu^{++}$, $Mn^{++}$이온이 효소의 활성을 촉진시켰으며, $Na^+$, $Ba^{++}$, $Mg^{++}$, $Fe^{++}$ 등의 이온에 의해서는 활성이 저해되었다. 효소저해제 중 maleic anhydride, iodine, 2,4-dinitrophenol을 처리하였을 때 활성저해가 관찰되어 효소의 histidine 잔기의 imidazol기가 활성부위로 판단되었다.

The optimum pH and temperature for endo-polygalacturonase activity from Jujube were 5.0 and $50^{\circ}C$. The range of its stability to pH was 4.0 to 5.0. The enzyme was inactivated about 35% by treatment at $70^{\circ}C$ for 1 hr. It was found that $Ag^+$, $Zn^{++}$ and $Mg^{++}$ increased the enzyme activity. In contrast, $Ba^{++}$, $Hg^{++}$, $Pb^{++}$, $Ca^{++}$, $Mn^{++}$, $Cu^{++}$, $Fe^{+++}$, $Na^+$ and $K^+$ decreased it. The enzyme was inactivated by treatment with maleic anhydride, iodine and 2,4-dinitrophenol. The results indicate that active site is a imidazole group on the enzyme.