RESUMEN

We have studied experimentally within the pH range of 3.65-5.5 at 50 degrees C the hydrolysis of cellobiose with Novozym 188, a commercial product with high beta-1,4-glucosidase activity derived from Aspergillus niger. We used wide variations in the conversion to be able to apply the integral method and thus determine that there is substrate and mixed product inhibition. Whether the SES triple compound contributes to the formation of glucose does not influence the fitting of the experimental results to the theoretical model to any significant extent. We have established how pH affects the kinetic parameters and ascertained that pH 4.3 is the optimum for the conversion of cellobiose into glucose.

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RESUMEN

We have studied the enzymatic hydrolysis of whey proteins at pH 8 and50 degrees C with two proteases of bacterial origin, MKC Protease 660 L, and one of animal origin, PEM 2500 S. Our results show that a greater degree of hydrolysis is achieved under the same experimental conditions with the bacterial proteases than with the animal one. In our interpretation of the results we propose a mechanism in which the hydrolytic reaction is a zero-order one for the substrate, and the enzyme denaturalizes simultaneously via a second-order kinetic process due to free enzyme attacking enzyme bound to the substrate. Our results also indicate that there is an irreversible serine-protease inhibitor in whey proteins. (c) 1994 John Wiley & Sons, Inc.

RESUMEN

Using high-pressure liquid chromatography we studied the distribution of molecular weights in whey-protein hydrolysates using the following commercially obtained proteases: Alcalasa 0.6 L and Protease 660 L, both bacterial in origin, and PEM 2500 S, of animal origin. In each of the systems, the range of molecular weights in the hydrolysate depended solely on the degree of hydrolysis (DH) achieved. For DH >/= 20, between 65% and 95% of the hydrolysate is made up of peptides with a molecular weight of less than 1,000 Da. (c) 1994 John Wiley & Sons, Inc.