Abstract
A commercial extract from the tongue and epiglottal region of suckling calf was partially purified to yield a calf pregastric lipase with activity against 4-nitrophenylalkanoate esters (C2-C12) at 37°C, pH 6.5. Maximum activity was detected against the C1O ester, 4-nitrophenyldecanoate. Lipase catalyzed hydrolysis of anhydrous milk fat showed preferential release of butyric acid. Integral values of pH and temperature were selected for determination of full Michaelis-Menten plots for hydrolysis of 4-nitrophenylacetate, and a kinetic surface was derived to characterize the activity of the enzyme preparation over a wide combination of these conditions. This complex surface revealed a region of maximum activity centered on optimal pH (pH ≤ 6.0) and temperature (43°C), although optima are not sharply delineated. A pK of 5.7 for the lipase-substrate dissociation constant and an activation energy of 37 kJ mol−1 were identified.
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