Synthesis of Glycosides by Transglycosylation of α-Amylase from Starch

전분으로부터 α-amylase에 의한 배당체의 합성

Glycosides were synthesized using transglycosylation reaction of amylase in water system. The glycosides synthesized in water phase by a-amylase with starch as a glycosyl donor and benzylalcohol as an acceptor were identified as benzylalcohol-${\alpha}$-glucoside (BG) and benzylalcohol-${\alpha}$-maltoside (BM) of which one molecule of benzylalcohol was bound to 1-OH of glucose. The final products were BG in reaction system of pH 5.0, and BM in that of pH 8.0. The transglycosylation reaction by ${\alpha}$-amylase were carried out in water system containing 50 mg starch, 50 mg benzylalcohol, and 10 units enzyme at $30-35^{\circ}C$ for 3 days. The synthesized BG was hydrolyzed to glucose and benzylalcohol by ${\alpha}$-glucosidase, while ${\alpha}$-amylase hydrolyzed BM to glucose and benzylalcohol-${\alpha}$-glucoside in pH 5.0. Maltotriose resemble structurally to BM was rapidly hydrolyzed to glucose and maltose by ${\alpha}$-amylase at pH 5.0, being slightly hydrolyzed at pH 8.0, but not transglycosylated in present of benzylalcohol.

수계에서 전분 가수분해 효소의 transglycosylation 반응을 이용하여 배당체(glycoside)를 합성하였다. Glycosyl donor인 가용성전분과 glycosyl acceptor인 benzylalcohol을 기질로 하여 ${\alpha}$-amylase에 의해 합성되는 배당체는 glucose의 1번 OH기에 benzylalcohol이 ${\alpha}$형태로 결합한 benzylalcohol-${\alpha}$-glucoside(BG)와 benzylalcohol-${\alpha}$-maltoside(BM)이었다. pH 5.0의 반응에서는 주로 BG가, pH 8.0의 반응에서는 BM만이 합성되는 특이한 반응양상을 보였다. Transglycosylation 반응의 최적조건은 가용성전분 50 mg/ml, benzylalcohol 50 mg/ml, 온도 $30-35^{\circ}C$, 효소량 10 unit/ml이었으며, 합성된 BG는 ${\alpha}$-glucodisase에 의해 glucose와 benzylalcohol로 가수분해되었으며 BM의 경우는 pH 5.0에서는 glucose와 BG로 가수분해되었으나 pH 8.0이상에서는 전혀 분해되지 않았다. BM과 구조적으로 유사한 maltotriose는 pH 5.0에서 glucose와 maltose로 가수분해 되었으나 transglycosylation반응은 거의 일어나지 않았으며 pH 8.0에서는 가수분해도 transglycosylation반응도 일어나지 않았다.