Catechol Oxidase Essay

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The different possible substrates for avocado catechol oxidase have very different Km’s and Vmax’s (Table 1). The Km’s range from 0.7 to 95, and the Vmax’s range from 0.58 x 105 to 17 x 105. The enzyme’s own substrates catechol has a Km of 6.5 and a Vmax of 5.4 x 105. Some of the substrates are better suited for catechol oxidase than others. For example, dopamine has a Km of 95 and a Vmax of 11 x 105. Both of these values are fairly high and would not make an effective substrate for catechol oxidase since the enzyme has a low affinity for the substrate. An example of a good alternative substrate would be 4-methylcatechol that has a low Km of 1.1 and a Vmax of 3.4 x 105. The enzyme now has a high affinity for the substrate and therefore requires less substrate to meet its Vmax. The substrate for the sweet potato catechol oxidase is N-phenylthiourea. In comparison to the possible substrates for catechol they both have hydrogen acceptor sites that can be used to hydrogen bond in the active site of the enzyme. Along with hydrogen bonding there may be some ionic bonding between some metal atoms in the active site of the enzyme and the substituents coming off of the benzene ring.…show more content…
However, the Vmax values for the avocado are much higher than the values for the banana or the mushroom. It would appear that the avocado and banana are more closely related because the enzyme showed similar affinity for the alternative substrates. This makes sense because on the tree of life mushrooms and green plants split long before monocots and dicots split. Meaning that monocots and dicots are more closely related than they are to mushroom. In this study, the avocado comes from a dicot and the banana comes from a

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