Rhizopus oryzae로부터 정제한 두가지형의 Glucoamylase의 효소적(酵素的) 특성(特性)

Enzymatic Characteristics of Two Forms of the Purified Glucoamylase from Rhizopus oryzae

Rhiz. oryzae가 생산(生産) 정제효소(精製酵素) glucoamylase I (G I) 과 glucoamylase II (G II) 의 gel filtration에 의(依)하여 추정(推定)된 분자량(分子量)은 120,000, 127,000이었다. glucoamylase I 과 II 의 등전점(等電点)은 각각(各各) pH 7.25. pH 7.75 이었고 반응(反應) 최적온도(最適溫度)는 다같이 $50^{\circ}C$, 안정온도범위(安定溫度範圍) 는 다같이 pH5.0부근(附近)이었으며 안정(安定)pH범위(範圍)는 각각(各各) $pH3.5{\sim}8.0$, $pH4.5{\sim}8.0$이었다. 가용성전분(可溶性澱粉)에 대(對)한 Michaelis 상수는 glucoamylase I 이 4.545mg/ml, glucoamylase II 가 5.560mg/ml이었다. glucoamylase I 은 $Hg^{++}$, $Pb^{++}$, p-CMB, IAA에 의하여, glucoamylase II는 $Hg^{++}$, $Mn^{++}$, p-CMB, IAA에 의하여 저해(沮害)되었다.

These experiments were conducted to investigate general enzymatic characteristics of two forms(glucoamylase I and glucoamylase II) of the purified glucoamylase produced by Rhizopus oryzae. Molecular weights of glucoamylase I and glucoamylase II estimated by Sephadex G-100gel filtration, were approximately 101,000 and 115,000, respectively, and those estimated by SDS-polyacrylamide gel electrophoresis being 120,000 and 127,000, respectively. Isoelectric points of the above enzyme were pH 7.25 and pH 7.75. The optimum temperature was $50^{\circ}C$ and the enzyme was stable below $45^{\circ}C$. Optimum pH of both glucoamylase I and glucoamylase II was about pH 5.0. The stable pH range of them were pH 3.5-8.0 and 4.5-8.0, respectively. Michaelis constants of glucoamylase I and glucoamylase II toward souluble starch were 4.545 mg/ml and 5.560 mg/ml, respectively. $Hg^{++}$, $Pb^{++}$, p-CMB and IAA were inhibitors of glucoamylase I and $Hg^{++}$, $Mn^{++}$, p-CMB and IAA were inhibitors of glucoamylase II.