The Preparation Of PLD And Study On The Synthetic Technique Of Phosphatidylserine

Phospholipases D (PLDs) are the enzymes that catalyse: (a)the hydrolysis of the terminal phosphodiester bond of glycerophospholipids, producing phosphatidic acid analogs and a free alcohol and (b) the exchange of the polar headgroup of the phosphorlipid, forming a new phosphoester bond, in the presence of an alcoholic nucleophile (transphosphatidylation reactions). PLDs are widespread in plants, but they also exist in animals, fungi and bacteria.In this paper, PLD are produced from Streptomyces by ferment. A strain, which can produce higher unit PLD, was obtained by a isolating and screening method. Then, this fungi was mutagenized by UV ligh and a strain was selected as producing PLD increased 27%.The culture supematants of selected strains were filtrated by a ultrafiltration membrane and the unit PLD was increased more than 2.8 times by ultrafiltration.In the study of phosphatidylserine synthesis process, the optimal reaction conditions is concluded: the serine(0.1g/ml) is dissolved into the culture supematants containing PLDs and adjust the pH value of 5.5. Then this solution is mixed with aether dissolving soybean phosphatide by 1:2 proportion. These materials are reacted under the agitation condition in 28℃. Finally, a mixture that contains 57% phosphatidylserine was obtained. Besides,a new reaction model for hydrolysis and transphosphatidylation recactions in aqueous-organic solvent system by PLD has been constracted.