Studies on I. A Reinvestigation of the Kinetics of the Urease Catalyzed Hydrolysis of Urea. II. Attempted Purification of the Adrenocorticotropic Hormone. III. Instrumental Adsorption Analysis. IV. The Effect of the Diphenyl Hydantoin (Dilantin) on the Ether Narcosis in the Cat

Abstract

In an investigation of the factors operative in the urease-catalyzed hydrolysis of urea in aqueous solutions, buffered at pH 7.0 with sodium or potassium phosphate, it has been found that both of the buffer components participate in the hydrolytic reaction. The buffer anion apparently functions as an activator and the buffer cation as an inhibitor. Sodium phosphate buffer displays a greater inhibitory action in the urease-catalyzed hydrolysis of urea than does an equivalent concentration of potassium phosphate buffer. After dialysis of urease solutions the activity in the presence of organic-inorganic buffers, e.g., ethylenedianine phosphate, was found to be greater than that of the initial preparation. The order of activation of the enzyme for the investigated anions as their ehtylenedianine salts is citrate > phosphate > maleate > sulphate > chloride > acetate. The activity of the enzyme increases with increased concentrations of these buffers. Attempted purifications of three samples of adrenocorticotropic hormone, RN 145, RN 146 and RN 147, resulted in the following conclusions. Paper chromatography revealed three components in RN 145, two in RN 146 with a possible third; and three in RN 147 with a possible fourth. Further work on sample RN 147 indicated five moieties by electrophoresis on paper, five with a possible sixth by dinitrophenylation and chromatography and a separation into five components by dialysis and fractional ammonium sulphate precipitation. The machine built for Instrumental Adsorption Analysis at the California Institute of Technology was put into operation. Successful separations of fatty acid mixtures and an isomeric cis-trans mixture were achieved. Attempted resolution of the adrenocorticotropic hormone indicated non-homogeneity. The administration of diphenyl hydantoin (dilantin) in a dose of fifty milligrams per kilogram bodyweight was observed to potentiate the narcotic effect of ether. It caused a forty percent decrease in blood ether concentration necessary to suppress the knee jerk of the cat. This supports the thesis that the depolarizing effects of ether and diphenyl hydantoin are additive and that depolarization is an important factor in the narcotic effect of ether on central conduction.</p