The Dismutation of Aldehydes by a Bacterial Enzyme

Abstract

Formaldehyde-resistant Pseudomonas putida F61 isolated from a soil sample showed high activities of formaldehyde dehydrogenase (EC 1.2.1.1) and a specific enzyme catalyzing the dismutation of formaldehyde to form methanol and formate. The latter enzyme, given the trivial name of formaldehyde dismutase, was purified to electrophoretic homogeneity from a cell-free extract of P. putida F61. The enzyme was a tetramer with a molecular weight of approximately 2.2 x 10⁵, and an isoelectric point of 4.8. The enzyme catalyzed the stoichiometric dismutation of formaldehyde and acetaldehyde to form a half mol of each of the corresponding alcohol and acid without addition of an electron acceptor, but it did not catalyze the dismutation of propionaldehyde, butyraldehyde and so on. The apparent Km for formaldehyde was found to be 350mM. One of the most unique properties of the enzyme was the catalytic activity of crossdismutation between two different aldehydes, such as formaldehyde/acetaldehyde, formaldehyde/propionaldehyde, and so on.