UTILIZATION OF ALCOHOLS BY PLANT AND MAMMALIAN PHOSPHOLIPASE-D

The transphosphatidylation reaction is a unique property of phospholip ase D (PLD). In this study, the abilities of plant and mammalian PLDs to utilize straight chain and branched alcohols for transphosphatidyla tion were analyzed and compared. PLD from peanut utilizes C1 to C8 pri mary alcohols and gives maximal reaction with butanol. In contrast, PL D from A7r5 vascular smooth muscle cells gives maximal reaction with p entanol and does not utilize octanol. Secondary and tertiary alcohols are not substrates for either enzyme. For branched alcohols, activity increases with distance from the alcohol to the branch point. Competit ion studies indicated that secondary alcohols cannot access the bindin g pocket. Thus, PLDs have a water/alcohol binding site with defined st eric and hydrophobic parameters.