University of Santo Tomas
Faculty of Pharmacy
EFFECT OF pH ON ENZYMATIC ACTIVITY
Abogado, Paula Isabel, Agustin, Nikka Rebecca, Andres, Mary Anne B., *Austria, Beatrice April, Baybay, Jan Miko Aaron 2BMT
pH greatly affects the activity of enzymes. There is a point or pH level where maximum activity of enzyme can be achieved, this is called optimum pH. Invertase was extracted from yeast and used as the detanured enzymes. Two sets of six test tubes were each added with different pH level of buffered solution: 1- 0.1, 2-0.3, 3-0.5, 4-1.7, 5-1.9, 6-1.11. On the first set, enzyme stock was added while on the second set denatured enzyme was added instead. Though this experiment was not performed due to the bad extraction of invertase and loss of time, the expected graph result is a hyperbola; where in optimum pH is at pH 5. And sucrose hydrolyzed has the same trend as the absorbance.
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and they are converted into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at significant rates.
Like all catalysts, enzymes work by lowering the activation energy for a reaction, thus increasing the rate of reaction.
Several factors, including enzyme concentration, pH of the reaction, and temperature, have an effect on enzymatic activity. This experiment focuses on the effect of ph on enzymatic activity.
pH is a measure of the concentration of hydrogen ions in a solution; the higher the hydrogen ion concentration, the lower the pH. Most enzymes function efficiently over a narrow pH range. A change in pH above or below this range reduces the rate of enzyme reaction considerably.
Usually, changes in the pH leads to breakage of ionic bonds between tertiary structures.  The enzyme begins to lose its...
 Boyer, Rodney. Enzymes I: Kinetics Mechanisms, and Inhibition. Biochemistry; 3rd edition, p. 143.
Figure 14 http://www.worthington-biochem.com/introbiochem/effectspH.html
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