INFLUENCE OF ORGANIC-SOLVENTS ON ENZYME CHEMOSELECTIVITY AND THEIR ROLE IN ENZYME-SUBSTRATE INTERACTION

Chemoselectivity of lipoprotein lipase from Pseudomonas specie is stro ngly influenced by solvation phenomena and can be modulated by changin g the reaction medium. Experimental results obtained from enzymatic ac ylation of L-Ser-beta-naphthylamide indicated that chemoselectivity de pends on the nature of hydrogen bonds taking place among the molecular species present in the reaction medium, Inverted selectivity was obse rved upon moving from hydrogen bond donor solvents to hydrogen bond ac ceptor solvents. Solvent hgdrophobicity can also influence chemoselect ivity inducing intramolecular electrostatic interactions which alter t he reactivity of the nucleophilic group(s). Solvation phenomena were s tudied by means of H-1 NMR. An explanation of interactions between the solvated substrate and the enzyme is also proposed.