Investigating The Reaction Rate And Specific Activity Of The Protein Extract

3761 Words16 Pages
Polyphenol Oxidase Analysis
By Natasha Patel
Miracosta College
1 Barnard Dr, Oceanside, CA 92056

Our goal in this experiment is to determine the reaction rate and specific activity of the protein extract. Also, the purpose of this lab is to characterize Vmax and Km for catechol and L-Dopa. Along with, determining whether the mode of inhibition by PTU is competitive or non-competitive? We performed a spectrometry analysis in order to determine the reaction rate of PPO, specific activity, and substrate- enzyme relationships among L-Dopa, catechol, and PTU. The reaction rate of polyphenol oxidase determined to be 0.04932957 μmin/min. By incoporating Beer’s Law, the specific activity of our protein extract was 0.2517127 μm/mgmin.In order to determine Vmax and Km for catechol and L-dopa we had to take averages from 3 dfferent groups. The Vmax for L-dopa determined to be 14.27, the ½ Vmax was 7.134, and the Km value was 0.485. The Vmax for catechol determined to be 10.00, ½ Vmax was 5.33, and the Km value was 0.38. The mode of inhibition by PTU determined to be non- competitive. The graph shows a rough hyperbolic trend with the slop increasing and then slowly making a curve towards the end for the catechol substrate concentration. However, the reaction with catechol and PTU portrayes a flat line. This is due to the fact that the increasing amount of substrate concentration had no effect on the reaction at all. Therefore, PTU was inhibiting the
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