Tryptophan tryptophylquinone

Conversion of methanol into formaldehyde by methanol dehydrogenase. A complex array of genes is involved in this oxidation and the dehydrogenase contains pyrroloquinoline quinone (PQQ) as a cofactor (references in Ramamoorthi and Lidstrom 1995). Details of its function must, however, differ from that of methylamine dehydrogenase that also contains a quinoprotein—tryptophan tryptophylquinone (TTQ). 

Methylamine dehydrogenase of Methylophilus methylotro-phus, proton transfer from the methylamine adduct of tryptophan tryptophylquinone (TTQ) CHs-amine vs. CDs-amine, transient kinetics studies of H-transfer step, H/D IE 5-40 °C, Ah/Ad = 16.8 0.5, AH 42.2 1.1 (H), 43.2 1.8 (D) kJ/mol, rate constant unchanged. 

This enzyme [EC 1.4.99.3], also known as amine dehydrogenase and primary-amine dehydrogenase, catalyzes the reaction of R-CH2-NH2 with water and an acceptor to produce R-CHO, ammonia, and the reduced acceptor. Tryptophan tryptophylquinone (TTQ) is the cofactor for this enzyme. See Resonance Raman Spectroscopy Topaquinone... 

Wang Y, Graichen ME, Liu A et al (2003) MauG, a novel diheme protein required for tryptophan tryptophylquinone biogenesis. Biochemistry 42 7318-7325... 

Fig. 6. Electron transfer complex between methylamine dehydrogenase and amicyanin from Paracoccus dentrificans (PDB Accession Code 2MTA). The distance shown is between eN of the redox cofactor tryptophan tryptophylquinone of methylamine dehydrogenase and the eN of the His-95 ligand of amicyanin.

FIGURE 1. The stracture of tryptophan tryptophylquinone. The C6 and C7 carbonyl carbons are labeled. 

Edwards, S. L., Davidson, V. L., Hyun, Y.-L., and Wingfield, P. T. 1995, Spectroscopic evidence for a common electron transfer pathway in two tryptophan tryptophylquinone enzymes. 

McIntire,W. S., Wemmer, D. E., Christoserdov, A. Y., and Lindstrom, M. E., 1991, A new cofactor in a prokaryotic enzyme Tryptophan tryptophylquinone as the redox prosthetic group in methylamine dehydrogenase, Science 252 817n824. 

Zhu, Z., and Davidson, V. L., 1998b, Redox properties of tryptophan tryptophylquinone enzymes. Correlation with stmcture and reactivity, J. Biol. Chem. 273 14254n 14260. 

Figure 3 Quinoprotein cofactors. TPQ, 2,4,5-trihydroxyphenylalanine quinone LTQ, lysine tyrosylquinone CTQ, cysteine tryptophylquinone TTQ, tryptophan tryptophylquinone.

We have been interested in the biological electron transfer between the cofactor tryptophan tryptophylquinone (TTQ) and a type I copper center." " The former is part of the membrane enzyme, methyl amine dehydrogenase (MADH), while the latter is the redox center of the blue copper protein. 

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