Highly efficient biosynthesis of phosphatidylserine by the surface adsorption-catalysis in purely aqueous media and mechanism study by biomolecular simulation

Abstract

• Efficient synthesis of PS by the surface adsorption-catalysis in aqueous solutions. • The enzymatic selectivity was improved and toxic solvents were completely avoided. • Adsorption regions and driving forces were confirmed by biomolecular simulations. • Diffusion processes of PC were reconstructed to illustrate biocatalytic processes. The adsorption of substrates/products on immobilized enzymes was a common bad phenomenon. A novel method was proposed to turn this “drawback” into treasure. Immobilized phospholipase D (PLD) acted as not only the catalyst, but also an “anchor molecule” facilitating the adsorption of hydrophobic substrate phosphatidylcholine (PC) in purely aqueous solutions. The PC loading even reached 96.7 %. The adsorption region and relevant driving forces were confirmed by the molecular docking and dynamics. The highest yield of phosphatidylserine (PS) reached 95.4 %. An “artificial interphase” was created, allowing a hydrophobic microenvironment for minimal hydrolysis. Simulation results indicated that adsorbed PC molecules would diffuse into the active center by rapid adsorption-desorption equilibrium or the parallel movement on the surface of PLD or combination diffusion. It explained why these “fixed” substrates could interact with the active center. Moreover, obtained PS was manufactured into microcapsules and toxic solvents were completely avoided in the whole process.