PhD ceremony: E.W. van Hellemond, 14.45 uur, Academiegebouw, Broerstraat 5, Groningen
Thesis: Discovery and characterization of oxidative biocatalysts. Styrene monooxygenase, putrescine oxidase, and alditol oxidase
Promotor(s): prof.dr. M.W. Fraaije, prof.dr. D.B. Janssen
Faculty: Mathematics and Sciences
Oxidative biocatalysts (enzymes) are an environmentally friendly alternative for the chemical oxidizing agents that are currently being used in industry. These enzymes are able to accelerate oxidation reactions in a mild manner and selectively form products that can be used as fine chemicals or in the pharmaceutical industry. In his thesis Erik van Hellemond describes the discovery and characterization of two new oxidative enzymes.
A new oxidative enzyme, ‘styrene monooxygenase’, was found in the ‘metagenome’, DNA that directly originates from soil. This monooxygenase oxidises aromatic and sulphur-containing compounds with the incorporation of oxygen. The second enzyme, ‘putrescine oxidase’, was discovered in the genome of the bacterium Rhodococcus erythropolis and oxidises amines. Like the styrene monooxygenase, this enzyme is dependent on a flavin cofactor, an organic compound that is bound in the enzyme. The binding appeared to be incomplete and therefore was studied in more detail.
A special class of oxidative enzymes is formed by the carbohydrate oxidases. In his thesis Van Hellemond gives an overview of these sugar oxidizing enzymes. For a recently discovered carbohydrate oxidase, alditol oxidase from Streptomyces coelicolor, he investigated which non-sugar compounds this enzyme oxidizes and which products are formed.
