Characterization of $\beta$-1,4-D-Glucan Glucanohydrolase Purified from Trichoderma koningii

Trichoderma koningii에서 분리한 $\beta$-1,4-D-glucan glucanohydrolase의 특성

  • 임대식 (서울대학교 자연과학대학 미생물학과) ;
  • 정춘수 (서울대학교 자연과학대학 미생물학과) ;
  • 강사욱 (서울대학교 자연과학대학 미생물학과) ;
  • 하영칠 (서울대학교 자연과학대학 미생물학과)
  • Published : 1991.05.01

Abstract

.betha.-1,4-D-Glucan glucanohydrolase(EC 3.2.1.4;F-II-IV) purified from Trichoderma koningii was identified as a glycoprotein containing 9% carbohydrate. Isoelectric point of the enzyme was estimated to be 4.9 and molecular weight was determined to be approximately 58,000. The porducts of p-nitrophenyl-cellobioside ($PNPG_{2}$) catalyzed by the enzyme were p-nitrophenol(PNP) and p-nitrophenyl-glucoside($PNPG_{1}$). The Km value for $PNPG_{2}$ was estimated to be 0.97 mM in case of the holoside lindage and 10.4 mM in case of the aglycon linkage and their kcat values were $1.8*10^{5}$$ min^{-1}$ and $7.5*10^{5}$ $min^{-1}$ respectively. The product of p-nitrophenyl cellotriose($PNPG_{3}$) was only $PNPG_{1}$. The Km value for $PNPG_{3}$ was 69.5 .$\mu$M and kcat was $1*10^{8}$ $min^{-1}$ which implicates that the enzyme have higher affinity and higher hydrolysis rate toward $PNPG_{3}$ than toward $PNPG_{2}$. The enzyme showed its optimal activity at pH 4.0-4.5 and at 60.deg.C. The effect of gluconolactone on the activity toward $PNPG_{2}$ showed competitive inhibition pattern but glucose and cellobiose did not. The enzyme contained a high content of acidic and hydroxylated amino acids in contrast to basic amino acids.

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