There is an optimal hydrogen ion concentration for the activity of each enzyme, and there are also upper and lower limits of reaction above or below which the enzyme is inactive or is destroyed.1 Enzymes of different origins, even though they act on the same substrate, vary in the hydrogen ion concentration at which they exert their greatest activity.2 In addition to the origin of the enzyme, the optimal reaction is affected by the type of buffer solution,3 the nature of the substrate,4
Chart 1.—Activity of duodenal amylase at ph 4.9 to 8.5. One-tenth cubic centimeter of duodenal contents, diluted 1: 4 with saline solution, was added to 10 cc. of 6 per cent starch suspension buffered with twentieth-molar phosphate solution, and the amylase activity was determined viscometrically at 34 C.8 5 6 7 8 9
Chart 2.—Activity of duodenal amylase at ph
ROTHMAN PE, WIDENER DC, DAVISON WC. OPTIMAL REACTION FOR STARCH-LIQUEFYING ACTIVITY OF DUODENAL AMYLASE OF INFANTS. Am J Dis Child. 1942;64(2):237–240. doi:10.1001/archpedi.1942.02010080029004
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