NMR monitoring of lipase-catalyzed reactions of prostaglandins: preliminary estimation of reaction velocities

The synthesis of methyl esters as well as acetylation of prostaglandins (PG) F2α and E2 and the corresponding methyl esters catalyzed by Candida antarctica lipase B (CALB) has been monitored by using 1H NMR spectroscopy in order to get a quantitative estimation of the velocities of the reactions occurring in the system. The apparent second-order rate constants of acetylation of the 11-OH group of PGs differed by up to two orders of magnitude while the difference between velocities of the CALB-catalyzed methylation of PGF2α and PGE2 was 2.5 times. The curves describing acetaldehyde formation were determined. The initial rapid consumption of water present on Novozym 435 was followed by an acetaldehyde formation matching the acetylation of prostaglandins.