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 × 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 pro-pionaldehyde, butyraldehyde and so on. The apparent Km for formaldehyde was found to be 350 mM. One of the most unique properties of the enzyme was the catalytic activity of cross-dismutation between two different aldehydes, such as formaldehyde/acetaldehyde, formaldehyde/ propionaldehyde, and so on.