Characterization of Choline Dehydrogenase fromPseudomonas aeruginosaA-16

Abstract

A choline dehydrogenase, which was present in the particulate fraction of the cell-free extract of Pseudomonas aeruginosa A-16, oxidized choline to betaine aldehyde without any dissociable coenzymes, while the enzyme, which was treated with Triton X-100, oxidized choline only with a supplement of phenazine methosulfate. The difference spectrum showed the presence of cytochrome-like components in the particulate. Km values for choline and phenazine methosulfate were 1.7 × 10⁻³ m and 1.4 × 10⁻⁴ m, respectively. The dehydrogenase was inhibited by SH-reagents such as p-chloromercuribenzoate and iodoacetic acid. Of a variety of substrates tested, only choline caused the enzymatic reduction of phenazine methosulfate. The estimation of choline was tried using the enzyme.