Calf Pregastric Esterase Catalyzed Hydrolysis of 4-Nitrophenylalkanoates: pH and Temperature Effects

Abstract

A commercial extract from the tongue and epiglottal region of suckling calf was partially purified to yield a calf pregastric enzyme with esterase activity against 4-nitrophenylalkanoate esters (C2-C12) at 370C, pH 7.2. The Km against 4-nitrophenylacetate was 0.023 mM, however, when 4-nitro-phenyldodecanoate was used as the substrate, the Km was 1.06 AM. The maximum activity was achieved at ca. 1.6 AM, which is similar to its critical micelle concentration. The reactivity is dependent upon pH. A pK of 7.23 which was obtained in the pH range 5.5-9.0 is indicative of a single ionizable residue. The activity dependence upon temperature of the partially purified enzyme was determined within the range of 25°C to 48°C and Eyring parameters were calculated.

The products from lipase-catalysed hydrolysis of bovine milkfat killHelicobacter pylori in vitro

“…Each fat emulsion was then divided into two 35‐mL aliquots. Freeze‐dried calf pregastric lipase (50 mg), partially purified as described previously (O'Connor et al , 1997), was added to one 35‐mL aliquot of each sample (milkfat or ModFat) to prime hydrolysis. The remaining 35‐mL aliquots were used as unhydrolysed controls.…”

Synergistic Effects of Surfactants on Kid Pregastric Lipase Catalyzed Hydrolysis Reactions

“…The work of Richardson and Nelson 2 did not clarify the debate on terminology, since the hydrolysis of esters or soluble triacetin may have also been due to the presence of an esterase in the enzyme preparation. There is clear evidence for the presence of esterase components in some pregastric lipase extracts, and their presence largely depends on the methods used for extraction. , The esterolytic component in the enzyme extracts showed those characteristics expected of an esterase, which only catalyzes the hydrolysis of water-soluble esters, e.g., p -nitrophenyl esters, but not monoacid triacylglycerols. , However, the purified lipolytic component in the pregastric extract was capable of catalyzing the hydrolysis of both soluble substrates and water-insoluble aggregates.…”