2MAD

THE ACTIVE SITE STRUCTURE OF METHYLAMINE DEHYDROGENASE: HYDRAZINES IDENTIFY C6 AS THE REACTIVE SITE OF THE TRYPTOPHAN DERIVED QUINONE COFACTOR

Replaces:  1MAD

Summary for 2MAD

• Entry DOI: 10.2210/pdb2mad/pdb
• Descriptor: METHYLAMINE DEHYDROGENASE (LIGHT SUBUNIT), METHYLAMINE DEHYDROGENASE (HEAVY SUBUNIT) (3 entities in total)
• Functional Keywords: oxidoreductase(chnh2(d)-deaminating)
• Biological source: Paracoccus versutus; More
• Cellular location: Periplasm: P22641 P23006
• Total number of polymer chains: 2
• Total formula weight: 51700.15

Authors

Huizinga, E.G.,Vellieux, F.M.D.,Hol, W.G.J. (deposition date: 1992-05-20, release date: 1994-01-31, Last modification date: 2024-06-05)

Primary citation

Huizinga, E.G.,van Zanten, B.A.,Duine, J.A.,Jongejan, J.A.,Huitema, F.,Wilson, K.S.,Hol, W.G.
Active site structure of methylamine dehydrogenase: hydrazines identify C6 as the reactive site of the tryptophan-derived quinone cofactor.
Biochemistry, 31:9789-9795, 1992

PubMed Abstract: To identify the reactive part of the orthoquinone function of the tryptophan-derived cofactor found in methylamine dehydrogenase (MADH), we have determined the crystal structures of MADH from Thiobacillus versutus inhibited by methylhydrazine and (2,2,2-trifluoroethyl)hydrazine. Extra electron density attached to C6 of the tryptophyl tryptophanquinone cofactor shows that this atom and not C7 is the reactive part of the ortho-quinone moiety. The density retained after hydrazine inhibition is much less extensive than expected, however, suggesting that partial breakdown of the inhibitors after reaction with the cofactor may take place. A detailed description is presented of the cofactor environment in an improved model of MADH which now includes information from the recently determined gene sequence of the cofactor-containing subunit [Ubbink, M., van Kleef, M.A.G., Kleinjan, D., Hoitink, C.W.G., Huitema, F., Beintema, J.J., Duine, J.A., & Canters, G.W. (1991) Eur. J. Biochem. 202, 1003-1012]. We hypothesize that Asp76 is responsible for proton abstraction from the alpha-carbon of the substrate during catalysis.

PubMed: 1390754
DOI: 10.1021/bi00155a036

Experimental method

X-RAY DIFFRACTION (2.25 Å)