engleski

Modelling of L-DOPA enzymatic oxidation catalyzed by L-amino acid oxidases from Crotalus adamanteus and Rhodococcus opacus

L-amino acid oxidases (L-AAO) are well known for their broad substrate specificity. L-amino acid oxidases from Crotalus adamanteus and Rhodococcus opacus were applied for biotransformation of 3, 4- Dihydroxyphenyl-L-alanine (L-DOPA) as a substrate to its corresponding alpha-keto acid. In this reaction hydrogen peroxide formed as a by-product causes chemical decarboxylation of alpha-keto acids and acts as competitive product inhibitor. Beef liver catalase was used to decompose it. It was shown that both enzymes were able to oxidize L-DOPA to corresponding products. L-AAO from R. opacus was more specific (lower value) and more active towards L-DOPA substrate than L-AAO from C. adamanteus. Its catalytic constant, k3, estimated by Levenspiel's method, was found to be tenfold higher than the one for L-AAO from C. adamanteus. L-AAO from R. opacus exhibits slightly L-DOPA inhibition, which is not the case for L-AAO from C. adamanteus. The biotransformations of L-DOPA were carried out in batch enzyme membrane reactor (EMR), as well as in the repetitive-batch EMR. The reactor and kinetics were modelled. Parameters were estimated by differential and integral method and presented in this article.

L-amino acid oxidase ; L-DOPA ; enzyme membrane reactor ; alpha-keto-acid ; enzyme kinetics ; modelling

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