Methylamine dehydrogenase (EC:1.4.99.3) a periplasmic quinoprotein found in several methyltrophic bacteria. Induced when grown on methylamine as a carbon source MADH catalyzes the oxidative deamination of amines to there corresponding aldehydes. MADH is a hetero- tetramer, comprised of two heavy chains (H) and two light chains (L). The H-chain forms a beta-propeller like structure.