Some Characteristics of Invertase Action and Their Significance in Interpreting the Nature of the Reaction

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Excerpt from Some Characteristics of Invertase Action and Their Significance in Interpreting the Nature of the Reaction: Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in the Faculty of Pure Science, Columbia University Historical. Brown (J. Chem. Soc., 81, 373 [1902]) observed that the rate of hydrolysis of sucrose in the presence of invertase reaches a maximum and remains constant above a certain substrate concentration, but did not actually determine what this concentration was. Nelson and Vosburgh (J. Am. Chem. Soc., 39, 790 [1919]) discussed a number of curves obtained from their own data and those of Michaelis and Menten (Biochem. Z., 49, 333 [1913]) relating the velocity of hydrolysis with the sucrose concentration and showed that the maximum rate of inversion was obtained in each case at about five grams of substrate per 100 c. c. of solution. At higher concentrations there was practically no change in velocity, while with less sugar the rate was smaller. The fact that two distinct invertase preparations, used at different temperatures (Nelson and Vosburgh worked at 37°, Michaelis and Menten at 25°), although causing different actual rates of hydrolysis, gave a maximum velocity of inversion at identical sucrose concentrations, is very striking for it indicates that there is some sort of phenomenon which is independent of the enzyme preparation and the temperature. The Relation Between the Sucrose Concentration and the Rate of Hydrolysis at Various Temperatures and Hydrogen Ion Concentrations. The fact that the temperature does not seem to affect the sucrose concentration at which the hydrolysis of the substrate reaches a maximum, but does affect the actual rate of the reaction appeared so striking that it was deemed desireable to obtain further data on this point. It was hoped that more light would thus be thrown upon the nature of the hydrolytic process. Hence, the influence of the temperature upon the relation between the sucrose concentration and the rate of the hydrolysis and, in addition to this, the influence of the hydrogen ion concentration were studied. Experimental. Curves were obtained in such ranges of temperature and hydrogen ion concentration (see Tables I - IV) as to make the results significant for the subsequent part of this investigation. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully, any imperfections that remain are intentionally left to preserve the state of such historical works.