The experiment is designed to determine whether the catalytic behavior of the enzyme is altered if the normal chemical environment is changed. The goal is to lower the concentration of lactase, so more excess enzyme is available to produce a greater amount of product for the same enzyme with the same volume in a sixty second period. The substrate o-nitrophenyl-B –D-galactopyranoside (ONPG) was used. A diluted Lact-Aid solution was the enzyme. The enzyme never reached saturation point in either the control or treatment. The use of fewer enzymes decreased the absorption of the ONPG. The 1/2X takes a longer amount of time to get to the same point as the 1X.
Enzymes are catalysts. Most are proteins. Enzymes bind temporarily to one or more of the reactants of the reaction they catalyze. In doing so, they lower the amount of activation energy needed and thus speed up the reaction. Lactase is an enzyme normally found in the small intestine that catalyzes the hydrolysis of the disaccharide lactose (milk sugar) to the monosaccharide galactose and glucose. The pH of the small intestine is alkaline (pH=8) and the temperature is 37C in humans. Salt concentrations on the order of 0.1 M (100 mM) are considered physiological. We worked to characterize lactase activity under optimal conditions such as are found in the small intestine. The usual means by which enzyme activity is assessed is through measurement of the rate of product formation or the rate of substrate disappearance could also be measured. The rate of lactose disappearance can not be measured by a spectronic-20, so the synthetic compound, ONPG is used as the alternative substrate. When ONPG is hydrolyzed by lactase, it yields the product 0-nitropenolate and galactose. O-nitropenolate is yellow in color and absorbs at a wavelength of 420 nm, so the spectronic-20 can be used to measure its appearance.
Our experiment was designed to determine whether the catalytic beha…

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