ENZYMATIC-HYDROLYSIS OF LONG-CHAIN ALKANOYLCHOLINES IN RAT INTESTINALLOOPS

Background: The hydrolysis of long-chain alkanoylcholines, presumably catalyzed by butyrylcholinesterase (EC 3.1.1.8), in rat intestinal loo ps was studied. The substances have earlier been found to be rapidly d egraded in vitro. Methods: Radiolabeled substrates were used, and a ra diochromatographic detection method was applied. Results and Conclusio n: The long-chain alkanoylcholines were rapidly hydrolyzed. The rates of the reaction and the chain-length dependence were similar to those reported earlier in vitro. At high substrate concentrations the hydrol ysis reaction was inhibited. This could be due to conformational chang es of the enzyme, caused by the adsorption of the cationic amphiphile, or to a decrease in the free substrate concentration after incorporat ion of the amphiphilic ester into the lipid layer of the cell membrane s. The enzymatic activity towards the substrates in different parts of the rat intestinal tract was also studied and found to be highest in the duodenum.