ENZYMATIC-HYDROLYSIS OF LONG-CHAIN ALKANOYLCHOLINES IN RAT INTESTINAL LOOPS

Background: The hydrolysis of long-chain alkanoylcholines, presumably catalyzed by butyrylcholinesterase (EC 3.1.1.8), in rat intestinal loops was studied. The substances have earlier been found to be rapidly degraded in vitro. Methods: Radiolabeled substrates were used, and a radiochromatographic detection method was applied. Results and Conclusion: 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 hydrolysis reaction was inhibited. This could be due to conformational changes of the enzyme, caused by the adsorption of the cationic amphiphile, or to a decrease in the free substrate concentration after incorporation of the amphiphilic ester into the lipid layer of the cell membranes. 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.