COMPUTATIONAL STUDIES ON THE MECHANISM OF BROMATE OXIDATION OF METHIONINE
COMPUTATIONAL STUDIES ON THE MECHANISM OF BROMATE OXIDATION OF METHIONINE
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Date
2015-09
Authors
HAMIDU, ABDUL
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Abstract
Oxidation of methionine is one of the degradation pathways of proteins. Bromate as a strong oxidizing agent can oxidize methionine to methionine sulphoxide. Computational chemistry was used to investigate the mechanism of oxidation of methionine by bromate at molecular level, using semi-empirical method at Parameterized method 3 and Modified Neglet of Diatomic Overlap level. The proposed mechanism involved seven consecutive steps. The heats of reaction of the computed proposed reaction mechanism were calculated to be -78.71kJ/mol,-3.5kJ/mol at 0oC and 25oC, respectively, at Parameterized method 3 level. While the heat of reaction based on Modified Neglect of Diatomic Overlap level of computation are -631.83kJ/mol and -533.82kJ/mol at 0oC and 25oC, respectively.The stoichiometry of the reaction was found to be 2:1 bromate to methionine, and the rate limiting step, step 2 involves the reaction between HBrO3 and methionine, which leads to the formation of intermediates that reacted and disproportionate to give the products. The equilibrium and rate constants obtained support the rate determining step.
Description
A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATESTUDIES, AHMADU BELLO UNIVERSITY, ZARIA, IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF A MASTER DEGREE IN PHYSICAL CHEMISTRY. DEPARTMENT OF CHEMISTRY, FACULTY OF SCIENCE, AHMADU BELLO UNIVERSTY, ZARIA, NIGERIA
Keywords
COMPUTATIONAL STUDIES,, MECHANISM,, BROMATE OXIDATION,, METHIONINE,