The Properties of Glucose Isomerase Produced by Streptomyces luteogriseus TH34

Streptomyces luteogriseus TH34가 생산하는 Glucose Isomerase의 특성

The enzymes were immobilized by treating the microbial cells in 0.05% chitosan and 0.28% glutaraldehyde solution. The activity of immobilized cell was about 535 IGIC/g. Glucose isomerase was purified by 6.5 times after homogenization using 60% $(NH_4)_2S0_4$ fractionation, DEAE-cellulose and Sephadex G-150 gel filtration. The molecular weight of enzyme was about 140,000 when it was measured by HPLC and the purified enzyme had only one band by electrophoresis. It showed good enzyme activity at pH 7.5 and $75^{\circ}C$. The optimum conditions for enzyme reactions were shifted to pH 7.0 and $80^{\circ}C$ when the enzyme was immobilized. The enzyme reaction was activated by the addition of 5~10 mM magnesium ion and the thermostability was improved by the addition of 0.25 mM cobalt ion. The enzyme activity was competitively inhibited by sugar alcohols.

토양에서 분리한 glucose isomerase 생산균주인 Streptomyces luteogriseus TH34를 0.05% chitosan과 0.28 glutaraldehyde를 이용하여 고정화시켜 역가가 기존 시제품보다 우수한 535IGIC/g인 효소를 얻었다. 한편 효소를 세포파괴 후 60% $(NH_4)_2S0_4$ fractionatioin, DEAE-Cellulose 및 Sephadex G-150을 이용하여 분리, 정제하여 6.3배 정제된 효소를 얻었고 고정화시킨 효소와 특성을 비교하였다. 효소의 분자량은 140,000이었고 분자량 35,000의 4개 subunits로 구성되어 있으며 최적 반응온도는 정제효소, 고정화효소에서 각각 $75^{\circ}C$, $80^{\circ}C$이고 열안전성은 공정화 효소가 높았으나 두 효소는 다 같이 $80^{\circ}C$이고 열안전성은 고정화 효소가 높았으나 두 효소는 다같이 $80^{\circ}C$에서 20분 처리시 역가 감소가 거의 없었다.