Distribution and Characterization of the Neurosteroid Acyltransferase from the Bovine Brain

소의 뇌에서 Neurosteroid Acyltransferase의 분포 및 특성에 관한 연구

  • Park, In-Ho (Department of Biotechnology, Ajou University) ;
  • Jo, Sung-Jun (Department of Biotechnology, Ajou University) ;
  • Jo, Do-Hyun (Department of Biotechnology, Ajou University)
  • 박인호 (아주대학교 생물공학과) ;
  • 조성준 (아주대학교 생물공학과) ;
  • 조도현 (아주대학교 생물공학과)
  • Published : 1997.04.28

Abstract

The enzymatic properties as well as its distribution in the cerebral region and subcellular organells were investigated for the neurosteroid acyltransferase from the bovine brain, which synthesize the fatty acid esters of the neurosteroids. The cerebellum region was the highest in NSAT activity while the cerebrum was the lowest with 50% of the cerebellar activity. The NSAT was found to be mainly localized in the microsomal fraction. The optimal temperature and pH were $40^{\circ}C$ and 4.9, respectively. When $^3H-DHEA$ was utilized as substrate, the $K_m$ and $V_{max}$ was $32.6\;{\mu}M$ and 4.86 nmole/mg protein/h, respectively. Under the same condition pregnenolone$({\Delta}^5P)$ was a competitive inhibitor with $K_i=22.8\;{\mu}M$ and testosterone was a uncompetitive inhibitor with $K_i=22.8\;{\mu}M$. This may suggest that the NSAT has a different conformation in the acylation of the ${\beta}-hydroxyl$ group at C-3 and C-17.