Methanol dehydrogenase of Methylomonas J: purification, crystallization, and some properties.

A methanol dehydrogenase [EC 1.1.99.8] was purified and crystallized from methanol-grown Methylomonas J (formerly Pseudomonas sp. J), an obligate methylotroph. Its molecular weight was estimated to be 135,000 by gel chromatography. The sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis revealed two bands and their molecular weights were approximately 60,000 and 10,000. The enzyme was relatively stable at pH 6 and 10, and was unstable at pH 8. The enzyme activity was lost at pH 4.0; however, the prosthetic group was not liberated from the enzyme. Its isoelectric point was pH 9.3. The visible-ultraviolet absorption, fluorescence, CD, and ESR spectra were measured. The amino acid composition was analyzed after separation of the two components. Primary alcohols and formaldehyde served as substrates. Phenazine methosulfate (PMS) was an effective electron acceptor of the enzyme in the presence of either NH4Cl or methylamine. The enzyme was inhibited partially by metal chelators and completely by Mn2+ and Co2+.