Properties and Activities of Nireogenase System of Azospirillum amazonensa Kp1

Azospirillum amazonense Kp1의 질소고정효소계의 활성 및 특성

  • 송승달 (경북대학교 자연과학대학 생물학과) ;
  • 김성준 (경북대학교 자연과학대학 생물학과) ;
  • 추연식 (경북대학교 자연과학대학 생물학과)
  • Published : 1990.06.01

Abstract

The maximum nitrogen fixation activity of the associative, microaerobic and acid tolerant bacteria, Azospirillum amazonense Kp1 was obtained with 0.2Kpa of $O_{2}$ and showed a reversible inhibition by the higher concentrations. Ammonium treatment caused a gradual inhibition of the activity up to 350mM. The nitrogenase systems were purified by gradient chromatography on DEAE-52 cellulose, heat treatment and preparative PAGE. The MoFe protein showed molecular weight of 210,000 including two nonidentical subunits with apparent molecular weights of 55,000 and 50,000 and an isoelectricpoint of 5.2 and contained 2, 24 and 28 atoms of Mo, Fe and acid labile S per molecule. The Fe protein revealed molecular weight of 66,000 including two types of subunits with molecular weights of 35,000 and 31,000 and an isoelectric point of 4.6, and contained 4 atoms of Fe and 6 atoms of S per molecule. The maximum specific nitrogenase activity attained 2,200 and 1,700nM $C_2H_4mg^{-1} min^{-1}$, respectively for MoFe and Fe proteins at pH7 and $35^{\circ}C$. The activity was lost after 10 and 30 days under the cold room ($4^{\circ}C$) condition for Fe and MoFe proteins, respectively.

Keywords

Azospirillum amozonense Kp1;nitrogen fixation;nitrogenase systems