title: [The release of flavin adenine dinucleotide upon local conformational transition in electron-transferring flavoprotein induced by trimethylamine dehydrogenase].
abstract: The electron-transferring proteins, trimethylamine dehydrogenase (TMAD) and electron-transferring flavoprotein (ETF) from the bacterium Methylophilius methylotrophus, were studied in vitro by fluorescence spectroscopy. Flavin adenine dinucleotide (FAD) was found to be capable of a slow and spontaneous release from ETF, which is accompanied by an increase in flavin fluorescence. At a rather high ionic strength (0.1 M NaCl or 50 mM phosphate), the FAD release is sharply activated by TMAD preparations that induce a local conformational transition in ETF. The values of tryptophan fluorescence polarization and lifetime and the use of the Levshin-Perrin equation helped show that the size of protein particles remain unchanged upon the TMAD and ETF mixing; i.e., these proteins themselves do not form a stable complex with each other. The protein mixture did not release flavin from ETF in the presence of trimethylamine and formaldehyde. In this case, a stable complex between the proteins appeared to be formed under the action of formaldehyde. Upon a short-term incubation of ETF with ferricyanide, FAD was hydrolyzed to flavin mononucleotide (FMN) and AMP. This fact explains the previous detection of AMP in ETF preparations by some researches. A fluorescence method was proposed for distinguishing FAD from FMN in solution using ethylene glycol. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 3; see also http://www.maik.ru.
authors.forename: A S
authors.initials: AS
authors.lastname: Lomtev
authors.forename: A G
authors.initials: AG
authors.lastname: Bobrov
authors.forename: N L
authors.initials: NL
authors.lastname: Vekshin
mesh_terms: D044927:Electron-Transferring Flavoproteins / Q000737:chemistry*; D019855:Ethylene Glycol / Q000737:chemistry; D005486:Flavin Mononucleotide / Q000032:analysis / Q000737:chemistry; D005182:Flavin-Adenine Dinucleotide / Q000032:analysis / Q000737:chemistry*; D020630:Methylophilus methylotrophus / Q000201:enzymology* / Q000378:metabolism; D010089:Oxidoreductases, N-Demethylating / Q000737:chemistry*; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence
chemical_list: D044927:Electron-Transferring Flavoproteins; D005182:Flavin-Adenine Dinucleotide; D005486:Flavin Mononucleotide; D010089:Oxidoreductases, N-Demethylating; C023186:trimethylamine dehydrogenase; D019855:Ethylene Glycol