The Effect of the Hydrogen Ion Concentration Tjpon the Starch-liquefying Actmty of the Amylase of Aspergillus Oryzb
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چکیده
In order to determine by viscometric methods (l), the effect of the hydrogen ion concentration of starch substrates upon the activity of the amylase of Aspergillus oryxa! (taka-diastase), it was first necessary to ascertain the effect of acid and alkali alone upon the viscosity of starch solutions. E$ect of Hydrogen Ion Concentration upon the Viscosity of Unbu$ered Starch Solutions.-10.2 gm. of commercial soluble starch (Merck), made according to Lintner’s method (2), were thoroughly mixed in 500 cc. of distilled water, boiled for 1 minute, and then autoclaved at a pressure of 18 pounds for 15 minutes. After cooling to 34”C., the solution was made 500 cc. with distilled water and filtered through muslin. 49 cc. of this solution (containing 1 gm. of soluble starch) were placed in each of nine 50 cc. volumetric flasks. The amount of HCl or NaOH required to adjust the reaction of each flask to the desired pH was added and the total volume was made 50 cc. with distilled water. The approximate amounts of acid or alkali required are indicated in Table I. These amounts differ for different lots of starch. The hydrogen ion concentration was determined by calorimetric methods (3). The viscosity of each of these nine solutions was determined in large Ostwald viscosimeters at 34°C. with accurate stop-watches. These results are expressed in Table II in terms of relative viscosity; i.e., the observed viscosity divided by the viscosity of water for the particular viscosimeter employed. A viscosity approximately two and a half times that of water is the most suitable for accurate measurements and this was produced
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تاریخ انتشار 2003