Enzyme Kinetics
Enzyme Kinetics
Marcos, Nelissa S.
Institute of Chemistry, University of the Philippines, Diliman, Quezon City 1101 Philippines
ABSTRACT
The rationale of the experiment is basically founded in the concept of reaction rates as affected by enzyme, and how the enzyme works is competed by a competitive inhibitor, thereby impeding the forward reaction. In this experiment, o-diphenol oxidase, an enzyme that causes the browning in fruits, was extracted from banana and reaction rate of this was established with various concentrations of catechol, the substrate, using the Michaelis-Menten, Lineweaver-Burk, Hanes-Woolf and Eadie-Hofstee plots. The plots were generated using the slope of absorbance readings against time plots. Absorbance can be used to detect reaction rate as this notes color intensity signaling product formation. The inhibition of o-diphenol oxidase by p-hydroxybenzoic acid is a competitive inhibitor, however, results in the experiment were not conclusive enough to determine that. Km values should increase if there is competitive inhibition, however, in this experiment, Km decreased in the four plots.
Introduction
Enzymes are protein catalysts that hasten the rate of a chemical reaction but are recovered fully at the end of the process. The mechanism follows temporary binding of the enzyme to the substrate and, as a result, lowering the activation energy needed to convert the substrate to product.
The rate at which an enzyme works is influenced by several factors. One of these is the concentration of substrate molecules for the higher the amount, the faster the enzyme molecules collide and bind with them. The concentration of substrate is represented as [S] and is expressed in molarity. Temperature is also considered because as it rises, molecular motion causing collisions between enzyme and substrate speed up. But as enzymes are proteins, there comes a point when the enzyme becomes denatured and ineffective. Presence of inhibitors affects
Marcos, Nelissa S.
Institute of Chemistry, University of the Philippines, Diliman, Quezon City 1101 Philippines
ABSTRACT
The rationale of the experiment is basically founded in the concept of reaction rates as affected by enzyme, and how the enzyme works is competed by a competitive inhibitor, thereby impeding the forward reaction. In this experiment, o-diphenol oxidase, an enzyme that causes the browning in fruits, was extracted from banana and reaction rate of this was established with various concentrations of catechol, the substrate, using the Michaelis-Menten, Lineweaver-Burk, Hanes-Woolf and Eadie-Hofstee plots. The plots were generated using the slope of absorbance readings against time plots. Absorbance can be used to detect reaction rate as this notes color intensity signaling product formation. The inhibition of o-diphenol oxidase by p-hydroxybenzoic acid is a competitive inhibitor, however, results in the experiment were not conclusive enough to determine that. Km values should increase if there is competitive inhibition, however, in this experiment, Km decreased in the four plots.
Introduction
Enzymes are protein catalysts that hasten the rate of a chemical reaction but are recovered fully at the end of the process. The mechanism follows temporary binding of the enzyme to the substrate and, as a result, lowering the activation energy needed to convert the substrate to product.
The rate at which an enzyme works is influenced by several factors. One of these is the concentration of substrate molecules for the higher the amount, the faster the enzyme molecules collide and bind with them. The concentration of substrate is represented as [S] and is expressed in molarity. Temperature is also considered because as it rises, molecular motion causing collisions between enzyme and substrate speed up. But as enzymes are proteins, there comes a point when the enzyme becomes denatured and ineffective. Presence of inhibitors affects
References: a) http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/EnzymeKinetics.html b) Hanes, CS (1932) c) Dowd, JE; and Riggs, DS (1965). "A Comparison of Estimates of Michaelis–Menten Kinetic Constants from Various Linear Transformations". Journal of Biological Chemistry 240 d) www.mystrica.com/Experiment.aspx?PageId=17