Abstract
In the previous report, the esterase activity in the crude pancreatic lipase was found to be remarkably stimulated by phytol isolated from Hizikia fusiformis. Hence, it was attempted to clarify the properties of this enzyme susceptible to the stimulation by phytol, on the basis of the substrate specificity and the effects of surface-active agents and physical state of substrate.
Neither cholesterol esterase and proteoesterase activities nor the esterase activities against p-nitrophenyl acetate, valeryl salicylate, and micellar monoglycerides were stimulated by phytol.
Thus, the enzyme susceptible to phytol was suggested to be a kind of carboxylesterase, acting on simple esters and glycerides of shorter-chain fatty acid only when they are in the state of “true solution” in the absence of bile salts.
It could not be excluded, however, that the lipase itself (possibly its esterase activity) might be partly responsible for the activation by phytol, from the observations on the effects of surface-active agents and of chain length of a series of aliphatic esters. It is not possible, therefore, to attribute this kind of enzyme to the so-called “typical” carboxylesterase, hydrolyzing aromatic as well as aliphatic esters, as is the case with liver esterase.
The stimulation of this enzyme by phytol was readily inhibited by the addition of bile salts, lecithin, Triton X-100, or urea, while the lipase activity was rather insensitive to them.
