title: Identification of the iron-sulfur center in trimethylamine dehydrogenase.
abstract: Trimethylamine dehydrogenase [trimethylamine:(acceptor) oxidoreductase (demethylating), EC 1.5.99.7] from a facultative methylotroph bacterium has a molecular weight of 147,000 and contains two types of prosthetic groups, one a covalently bound organic chromophore of uncertain structure and the other containing iron and labile sulfur (S*). The structure of the Fe-S* center has been investigated by reactions of the enzyme with sodium mersalyl, o-xylyl-alpha,alpha'-dithiol, and p-methoxybenzenethiol in a 4:1 vol/vol hexamethylphosphoramide/water reaction medium, which destabilizes tertiary structure. Mersalyl treatment results in reduction of visible absorbance consistent with the presence of a 4-Fe center of the ferredoxin type. Reaction with thiols effects partial bleaching of the organic chromophore, as established by separate studies of a detached chromophore peptide, and results in removal (extrusion) of the core unit of the Fe-s* center in the form of the complexes [Fe4S*4(S2-o-xylyl)2]n2n- and [Fe4S*4(SC6H4OMe)4]2-, which were identified by absorption spectra. These results, in conjunction with control extrusion reactions of oxidized ferredoxins from spinach and Clostridium pasteurianum, establish that trimethylamine dehydrogenase contains one Fe4S*4 core unit most probably present as a ferredoxin-type, cysteinate-ligated cluster [Fe4S*4(S-Cys)4].
mesh_terms: D001419:Bacteria / Q000201:enzymology; D001665:Binding Sites; D007501:Iron / Q000032:analysis; D007506:Iron-Sulfur Proteins; D008667:Metalloproteins; D000587:Oxidoreductases Acting on CH-NH Group Donors; D011485:Protein Binding; D011487:Protein Conformation; D013455:Sulfur / Q000032:analysis
chemical_list: D007506:Iron-Sulfur Proteins; D008667:Metalloproteins; D013455:Sulfur; D007501:Iron; D000587:Oxidoreductases Acting on CH-NH Group Donors
references.citation: J Biol Chem. 1963 Dec;238:3899-913
references.pmid: 14086723
references.citation: Biochem Biophys Res Commun. 1976 Aug 23;71(4):1289-95
references.pmid: 971314
references.citation: J Am Chem Soc. 1974 Jun 26;96(13):4168-78
references.pmid: 4854592
references.citation: J Am Chem Soc. 1974 Jun 26;96(13):4159-67
references.pmid: 4854591
references.citation: J Am Chem Soc. 1973 May 30;95(11):3523-34
references.pmid: 4708377
references.citation: J Biol Chem. 1974 Mar 10;249(5):1587-98
references.pmid: 4150391
references.citation: Anal Biochem. 1967 Aug;20(2):325-34
references.pmid: 4293646
references.citation: Annu Rev Biochem. 1974;43(0):461-507
references.pmid: 4605451
references.citation: Annu Rev Biochem. 1973;42(0):159-204
references.pmid: 4599384
references.citation: J Biol Chem. 1976 Apr 10;251(7):2105-9
references.pmid: 178656
references.citation: Eur J Biochem. 1975 May;54(1):185-94
references.pmid: 168076
references.citation: Arch Biochem Biophys. 1975 Jul;169(1):102-7
references.pmid: 168814
references.citation: Proc Natl Acad Sci U S A. 1975 Dec;72(12):4795-9
references.pmid: 174076
references.citation: Biochem J. 1974 Dec;143(3):555-67
references.pmid: 4462741
references.citation: Biochim Biophys Acta. 1976 May 13;429(3):705-19
references.pmid: 1268229
references.citation: Biochem Biophys Res Commun. 1976 May 17;70(2):582-8
references.pmid: 938514
references.citation: J Am Chem Soc. 1975 Jan 22;97(2):463-4
references.pmid: 1133364