STudies on the Cellulolytic Enzymes of Stachybotrys atra

Stachybotrys atra에서 추출한 섬유소분해효소에 관한 연구 II

  • 김영민 (연세대학교 생물학과) ;
  • 김은수 (연세대학교 생물학과)
  • Published : 1976.09.01

Abstract

A cellulase fraction (F IV-1) purified to about 8-folds was obtained from crude cellulase prepared from the wheat bran culture of S.atra. The partial purification of the enzyme was made by DEAE Sephadex and Sephdex cloumn chromatography in conjuction with ammonium sulfate precipitation. After stading at various pH's for 22 hours at $20^{\circ}C$, F IV-1 was most stable at pH 5.0 but when the enzyme fraction was stood for 74 hours, the point of pH stability was raised to around pH 6.0-7.0. After heating at various temperatures for 1 hour, F IV-1 was most stable at $20^{\circ}C$. The optimal enzyme activities of F IV-1 were seen at pH 6.0 and $50^{\circ}C$. The optimal concentrations of $Zn^{++}\;and\;Ca^{++}$ for the activities of crude cellulase were 6 and 4 mM respectively, but $Ca^{++}$ inhibited the enzyme activity at concentrations below 2 mM and above 6mM. Both $Cu^{++}\;and\;Mn^{++}$ ions inhibited cellulase activities and a ocmplete inactivation of crude cellulase was achieved at concentratioins of 5 and 2 mM of ions respectively. When Na-CMC was used as substrate, the Km values of crude cellulase and F IV-1 were calculated to be $5{\times}10^{-4}\;and\;2{\times}10^{-5}mM$, and V values 32 and 1.35 mmoles/hour, respectively. The Ki values of $Mn^{++}$ for crude cellulase and F IV-1 were found to be $8{\times}10^{-2}\;and\;3{\times}10^{-2}\;mM\;while\;those\;of\;Cu^{++}\;were\;at\;2{\times}10^{-1}\;and\;1{\times}10^{-1}\;mM\;respectively.\;Both\;Mn^{++}\;and\;Cu^{++}$ showed competitive inhibition with substrate.

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