Estimation of the Prosthetic Group of Laccase Secreted from Pleurotus ostreatus

Pleurotus ostreatus에서 분비된 Laccase의 보결단 추정

  • 윤홍덕 (서울대학교 자연과학대학 미생물학과) ;
  • 신광수 (서울대학교 자연과학대학 미생물학과) ;
  • 강사욱 (서울대학교 자연과학대학 미생물학과) ;
  • 하영칠 (서울대학교 자연과학대학 미생물학과) ;
  • 정가진 (서울대학교 자연과학대학 미생물학과) ;
  • 김규중 (강릉대학교 생물학과)
  • Published : 1991.09.01

Abstract

Extracellular laccase secreted from Pleurotus ostreatus was activated by $Cu^{2+}$ and $Cu^{+}$ . The enzyme was strongly inactivated by 8-hydroxyquinoline, potassium cyanide, sodium azide, sodium bisulfite and 2-mercaptoethanol. The two ionogenic groups, which have pKa values of 5.60-5.70 and 6.70-6.85 respectively, were found to relate with the active site of this enzyme. The oxidation reactions were brought about by initial single electron transfer process on the active site. The enzyme was found to be a metalloprotein which had about 3.9 cupric ions per molecule of protein as a prosthetic group. The enzyme showed a strong peak at 605 nm and a weak shoulder at 330 nm in UV-Visible absorption spectrum. Both signals disappeated upon treatment of the enzyme with 4 electron equivalent ascorbate. These results indicate that type I Cu peak and type III Cu shoulder are present in laccase.

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