Studies on the screening and properties of Raw Starch Saccharifying Microorganism(II) - Purification and characterization of raw starch-digesting enzyme from Aspergillus sp. SN-871 -

생전분(生澱粉) 자화성(資化性) 미생물(微生物)의 분리(分離)와 성질(性質)에 관(關)한 연구(硏究)(II) - Aspergillus sp. SN-871이 생산하는 생전분 분해효소의 정제 및 특성 -

A raw starch saccharifying enzyme from Aspergillus sp. SN-871 was purified by ammonium sulfate precipitation, DEAE-cellulose column chromatography, CM-Sephadex C-50 column chromatography and Sephadex G-75 gel filtration. The specific activity of purified enzyme was 18 fold and the yeild was 13.40%. The molecular weight of the purified enzyme was estimated as approximately 40,000 dalton by the method of Andrews gel filtration. The optimum pH and temperature for this enzyme were found to be 4 and $40^{\circ}C$, respectively and the stable range of pH was 2 to 5. The enzyme was themostable at below $60^{\circ}C$ and inactivated at $70^{\circ}C$. It showed a tendency to increase the enzyme activity under the presence of 0.01 M $BaCl_2$, but under 0.01 M$Pb(NO_3)_2$, $AgSO_4$, and $K_3Fe(CN)_6$ and citric acid etc. inhibited it completely. The substrate specifity of enzyme showed a tendency to increase the enzyme activity under addition of dextrin and glycogen, but under saccharose inhibited it. COD removal rate of Aspergillus sp. SN-871 was approximately 67 to 68%.

1. $(NH_4)_2SO_4$침 전, DEAE-cellulose column chromatography, CM-Sephadex C-50 및 Sephadex G-75 gel filtration에 의하여 정제된 효소는 조효소보다 18배가 높았으며 회수율은 13.40%였다. 2. 겉보기 분자량은 약 40,000dalton이었다. 3. 최적 pH와 온도는 4.0, $40^{\circ}C$일 때이며, 안정범위는 pH2.0에서 pH5.0, 온도는 $60^{\circ}C$ 이하이었다. 4. 금속이온 첨가에 의한 영향은 $10^{-2}M$ $BaCl_2$첨가시 효소활성이 증가되었으며, $10^{-2}M$ $Pb(NO_3)_2$, $K_3Fe(CN)_6$, $AgSO_4$와 $ZnSO_4$첨가시는 효소활성이 완전히 저해되었다. 5. 각종 유기화합물 첨가에 의한 효소의 영향은 citric acid 첨가시 효소활성이 현저히 저해되었다. 6. 기질 특이성을 보면 dextrin과 glycogen을 기질로 하였을 때는 효소활성이 증가하였으나 saccharose 첨가시에는 현저히 저하되었다. 7. COD 제거율을 측정한 결과는 67에서 68% 정도이었다.