Purification and Properties of $\alpha$-Glucosidase from Mococcus halophilus

Pediococcus halophilus로부터 생성한 $\alpha$-Glucosidase의 정제 및 특성

A bacterial strain No. 2, which highly produced a-glucosidase, was isolated from Kimchi and identified to be a similar species of Pediococcus halophilus. This enzyme was purified by protamine sulfate, ammonium sulfate fractionation, ion exchange and gel filtration. The maximal a-glucosidase activity was observed at pH 6.0 and this enzyme was stable at pH 6.0~ 7.5. The optimum temperature of this enzyme activity was $37^{\circ}C$, but enzyme activity was gradually lost above $37^{\circ}C$. This enzyme was activated by 10 mM MgCh and inhibited by 10 mM mercaptoethanol. The kinetics of PNPG(p-Nitrophenyl-a-D-glucopyranoside) and maltose were Kp0.52 mM/27.5 pg protein, $V_{max}$= 0.021 mM/min 27.5 ${\mu}g$ protein and $K_m$= 0.32 mMD7.5 ${\mu}g$ protein, $V_{max}$= 0.025 mM/min 27.5 ${\mu}g$ protein, respectively. The molecular weight of $\alpha$-glucosidase was about 37, 000.

호화전분이 포함된 김치로부터 유산을 생성하는 6균주를 분리하였으며, 분리된 균주는 soluble starch가 포함된 APT 액체배지에서 분리균주의 생육과 $\alpha$-glucosidase 활력이 우수한 No.2 균주를 선별하였다. 이 분리균은 Pediococcus halophilus 또는 그 유연균으로 동정되었다. 효소의 정제는 protamine sulfate에 의한 핵산의제거, ammonium sulfate 분획, gel filtration 및 ion exchange 등의 4단계 정제과정을 거친 결과 20.17배 정제되어 단일 band 효소로 분리되었다.