Methylamine dehydrogenases of Pseudomonas sp. J and Pseudomonas AM1. Study on subunit structure by dimethyl...

Methylamine dehydrogenase (MW: 105,000) of Pseudomonas sp. J was treated with a bifunctional cross-linking reagent, dimethyl suberimidate. Cross-linked proteins having different molecular -eights of 53,000, 64,000, 80,000, 93,000, and 103,000 were found in addition to 13,000 (light subunit) and 40,000 (heavy subunit) by SDS polyacrylamide gel electrophoresis. Isolated light and heavy subunits were separately treated with the reagent. The product having a molecular weight of 80,000 was found to be a major cross-linked protein for the heavy subunit but no product was found for the light subunit. A similar electrophoretic pattern was also obtained for the reconstituted enzyme from the subunits of Pseudomonas sp. J and for methylamine dehydrogenase of Pseudomonas AM1. These results suggest that methylamine dehydrogenases obtained from these two bacteria are both the alpha2beta2-type subunit enzyme and have a geometrically analogous subunit structure.