발아초기(發芽初期) 녹두의 Alkaline Inorganic Pyrophosphatase의 효소적(酵素的) 성질(性質)에 대하여

Some Properties of Partially Purified Alkaline Inorganic Pyrophosphatase from Mung-bean (Phaseolus radiatus) Seedling

발아초기 녹두의 부위별 alkaline inorganic PPase의 활성변화 및 잎 부위에서 부분 정제하여 얻은 효소를 이용하여 효소적 성질을 조사한 결과를 요약하면 다음과 같다. 1. 잎 부위가 타 부위보다 약 2~4배의 더 높은 활성을 나타냈으며 발아가 진행됨에 따라 잎과 뿌리 그리고 지엽에서는 효소 활성이 초기에 증가하다가 점차 감소하는 경향을 보인 반면, 상배축에서는 초기부터 계속 감소하였으며 하배축에서는 계속 증가하는 경향을 보였다. 2. 정제 과정동안 23.9%의 수율로 86배가 정제되었으며 전기 영동상의 Rm value는 0.35였으며 homogenenity는 아니었고, Km value는 0.89mM로 나타났다. 3. 이 효소는 $Mg^{2+}$에 대해 대단히 Specific하였으며 $Cu^{2+}$와 $Fe^{2+}$도 $Mg^{2+}$에 비해 각각 56%, 55%의 activating effect를 나타냈다. 그러나, $Cu^{2+}$, $Zn^{2+}$, $Mn^{2+}$, $Co^{2+}$와 $Ni^{2+}$은 이 효소에 대해 저해체로 작용하였다. 4. 이 효소는 pH 8-9와 $50^{\circ}C$에서 최대의 활성을 보였으며 열에 대해서도 상당히 안정하였다.

Time course of alkaline inorganic PPase activity with different parts of mung-bean sprout and some properties of partially purified enzyme from mung-bean leaves were investigated. The enzyme activity in leaf, root and cotyledon showed a tendency to increase at an early stage and then decrease gradually as germination continued. However, the crude homogenate of epicotyl showed the continuous decline of the enzyme activity but that of hypocotyl showed the continuous increase. In particular, the enzyme activity of leaf fraction was about 2-4 times as high as those of other fractions. The specific activity of the leaf enzyme was increased 86-fold, with a 23.9% yield, upon purification procedures. The purified enzyme from leaves had the Rm value of 0.35 and was not homogenous when judged by disc gel electrophoresis. Using tetrasodium pyrophosphate as a substrate, the apparent Km value for the partially purified enzyme was 0.89 mM. The enzyme was highly specific for $Mg^{2+}$ $CU^{2+}$ and $Fe^{2+}$ was also showed the activating effect of 56% and 55% with $Mg^{2+}$, respectively. However, $Ca^{2+}$), $Zn^{2+}$, $Mn^{2+}$, $Co^{2+}$ and $Ni^{2+}$ acted as inhibitors for the enzyme. The pH optimum for the enzyme shifted from 9.0 to 8.0 as the concentration of $Mg^{2+}$ was increased. The enzyme from mun-bean leaf was the most active at $50^{\circ}C$ and considerably stable on heat.