A PAF‐acetylhydrolase activity in Tetrahymena pyriformis cells

[摘要]

Our study provides evidence for the existence of an acylhydrolase activity in Tetrahymena pyriformis cells, capable of hydrolizing the sn-2 ester bond of the PAF molecule. This activity is mainly distributed in the microsomal fraction (76.5% of total) and has properties similar to the mammalian PAF-acetylhydrolase since it is Ca²⁺-independent, acid-labile, is inhibited by DFP and PMSF but it is not affected by egg yolk phosphatidylcholine. This microsomal acylhydrolase has apparent K_m and V_max values of 1.56 μM and 373 pmols - mg - min respectively. This is the first report of the existence of a PAF-acetylhydrolase activity in a non-mammalian cell.

[学科分类] 生物化学/生物物理

[关键词] Platelet-activating factor;PAF;Phospholipase A2;PAF-acetylhydrolase;Lipid metabolism;(Tetrahymena pyriformis);PAF;platelet-activating factor;PAF-AH;PAF-acetylhydrolase;PLA2;phospholipase A2;[3H]PAF;1-O-hexadecyl-2-[3H]acetyl-sn-glycero-3-phosphocholine;[3H]alkyl-PAF;1-O-[1′;2′-3H]hexadecyl-2-acetyl-sn-glycero-3-phosphocholine;BSA;bovine serum albumin;TCA;trichloroacetic acid;DFP;diisopropyl-fluorophosphate;PMSF;phenylmethylsulfonylfluoride