Korean J Prev Med.  1974 Oct;7(1):107-113.

Effect of External Factors on Diastase Activity in Water

• Yoon BS
• Hyun HS
• Paek NW

Abstract

Many factors exert an influence on enzyme activity and thus on the rate of reactions that they catalyse. The most important of these factors are pH, temperature, substrate concentration, and the concentration of some inhibitors present. A solution of the enzyme diastase, which breaks down molecules of the polysaccharide starch to the disaccharide maltose by hydrolysis, was provided. Activity of these enzyme was measured by the rate at which starch was removed from the reaction mixture. These experiments were designed to study this reaction rate under varying conditions and the following results were obtained. 1. The range of optimum pH for this enzyme at room temperature was 4.0-7.0 and the optimum pH was 5.0. 2. The range of optimum temperatures for this enzyme at pH 7.0 was 30-50 degrees C and the optimum temperature was 40 degrees C. 3. The relationship between the enzyme activity and substrate concentration could be expressed by the Michaelis-Menten equation. The limiting velocity of these enzyme at room temperature and pH 7.0 was 415 microgram starch removed/ml of reaction mixture/min and Km, Michaelis constant, was 343 microgram/ml. 4. Inhibitors NaCl and HgCl2 blocked this enzyme activity completely at 1% and 0.01% respectively.

MeSH Terms

Amylases*
Hydrogen-Ion Concentration
Hydrolysis
Maltose
Mercuric Chloride
Starch
Water*
Amylases
Maltose
Mercuric Chloride
Starch
Water