PMID:10220347

Citation	Wagner, MA, Khanna, P and Jorns, MS (1999) Structure of the flavocoenzyme of two homologous amine oxidases: monomeric sarcosine oxidase and N-methyltryptophan oxidase. Biochemistry 38:5588-95
Abstract	Monomeric sarcosine oxidase (MSOX) and N-methyltryptophan oxidase (MTOX) are homologous enzymes that catalyze the oxidative demethylation of sarcosine (N-methylglycine) and N-methyl-L-tryptophan, respectively. MSOX is induced in various bacteria upon growth on sarcosine. MTOX is an E. coli enzyme of unknown metabolic function. Both enzymes contain covalently bound flavin. The covalent flavin is at the FAD level as judged by electrospray mass spectrometry. The data provide the first evidence that MTOX is a flavoprotein. The following observations indicate that 8alpha-(S-cysteinyl)FAD is the covalent flavin in MSOX from Bacillus sp. B-0618 and MTOX. FMN-containing peptides, prepared by digestion of MSOX or MTOX with trypsin, chymotrypsin, and phosphodiesterase, exhibited absorption and fluorescence properties characteristic of an 8alpha-(S-cysteinyl)flavin and could be bound to apo-flavodoxin. The thioether link in the FMN-containing peptides was converted to the sulfone by performic acid oxidation, as judged by characteristic absorbance changes and an increase in flavin fluorescence. The sulfone underwent a predicted reductive cleavage reaction upon treatment with dithionite, releasing unmodified FMN. Cys315 was identified as the covalent FAD attachment site in MSOX from B. sp. B-0618, as judged by the sequence obtained for a flavin-containing tryptic peptide (GAVCMYT). Cys315 aligns with a conserved cysteine in MSOX from other bacteria, MTOX (Cys308) and pipecolate oxidase, a homologous mammalian enzyme known to contain covalently bound flavin. There is only one conserved cysteine found among these enzymes, suggesting that Cys308 is the covalent flavin attachment site in MTOX.
Links	PubMed Online version:10.1021/bi982955o
Keywords	Amino Acid Sequence; Bacillus/enzymology; Binding Sites; Coenzymes/chemistry; Escherichia coli/enzymology; Escherichia coli Proteins; Flavin Mononucleotide/chemistry; Flavin-Adenine Dinucleotide/chemistry; Flavins/analysis; Molecular Sequence Data; Oxidoreductases/chemistry; Oxidoreductases, N-Demethylating/chemistry; Oxidoreductases, N-Demethylating/isolation & purification; Sarcosine/chemistry; Sarcosine Oxidase; Sequence Alignment; Sequence Homology, Amino Acid
edit table

Significance

You can help EcoliWiki by summarizing why this paper is useful

Useful Materials and Methods

You can help Ecoliwiki by describing the useful materials (strains, plasmids, antibodies, etc) described in this paper.

Annotations

<annotationlinks/>

EcoliWiki Links

Add links to pages that link here (e.g. gene, product, method pages)

References

See Help:References for how to manage references in EcoliWiki.