전분으로부터 Amyloglucosidase의 당전이반응에 의한 배당체의 합성

Synthesis of Glycoside by Transglycosylation of Amyloglucosidase from Starch.

수계에서 전분 가수분해효소의 transglycosylation반응을 이용하여 배당체(glycoside)를 합성하였다. Glycosyl donor인 starch와 glycosyl acceptor인 benzylalcohol을 반응기질로 선택하였다. 시판되는 9종의 당가수분해효소의 transglycosylation활성을 조사한 결과 glucose와 한 종류의 glycoside만을 생산하는 amyloglucosidase(from Rhizopus sp.)를 반응효소로 선정하였다. Amyloglucosidase에 의해 합성된 배당체는 여러 가지 분석을 통해 glucose의 1번 OH기에 benzylalcohol이 ${alpha}$형태로 결합된 benzylalcohol-${alpha}$-glucoside(BG)임을 확인하였다. 수계에서 이 효소에 의한 transglycosylation 반응의 최적조건은 starch 50mg/$m\ell$, benzylalcohol 50 mg/ml, 온도 45$^{\circ}C$, 효소량 10 unit/ml, pH 5.0, 반응시간 32시간이었으며 합성된 BG는 amyloglucosidase에 의해서는 분해되지 않았고 ${alpha}$-glucosidase에 의해 glucose와 benzylalcohol로 가수분해되었다.

Glycosides were synthesized using transglycosylation reaction of amylase in water system. Starch as a glycosyl donor and benzylalcohol as an acceptor were selected as substrates of transglycosylation reaction. Among tested 9 commercial amylase, amyloglucosidase from Rhizopus sp. had high activity for transglycosylation from starch. The glycoside synthesized in water phase by amyloglucosidase was identified as benzylalcohol-${alpha}$-glucoside (BG) of which one molecule of benzylalcohol was bound to 1-OH of glucose. The transglycosylation reaction by amyloglucosidase were carried out in reaction system containing 50 mg starch, 50 mg benzylalcohol, and 10 units enzyme in pH 5.0 at 45$^{\circ}C$. The synthesized BG was hydrolyzed by ${alpha}$-glucosidase to produce glucose and benzylalcohol.