Open AccessCovalently Bound Flavin in d ‐6‐Hydroxynicotine Oxidase from Arthrobacter oxidans
Author(s) -
Möhler Hanns,
Brühmüller Margarete,
Decker Karl
Publication year - 1972
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1972.tb01969.x
Subject(s) - flavin group , riboflavin , chemistry , flavoprotein , cofactor , flavin adenine dinucleotide , histidine , flavin mononucleotide , oxidase test , quenching (fluorescence) , stereochemistry , covalent bond , hydrolysis , enzyme , biochemistry , organic chemistry , fluorescence , physics , quantum mechanics
A substituted riboflavin (HNO‐flavin) was isolated from d ‐6‐hydroxynicotine oxidase. It was obtained from flavin peptides by hydrolysis with 6 N HCl at 95°C or with aminopeptidase M. The riboflavin derivative had the spectral characteristics of 8α‐substituted flavins. It showed a pH dependence of fluorescence with a pK of 4.65 and 86%, quenching at pH 7. In thin‐layer chromatography it was identical with 8α‐( N ‐3‐histidyl)‐riboflavin. Hydrolysis of HNO‐flavin in 6N HCl at 125°C liberated 1 mol histidine per mol flavin as shown by amino acid analysis. Since FAD is the coenzyme of d ‐6‐hydroxynicotine oxidase, these results are taken as evidence that this enzyme contains 8α‐( N ‐3‐histidyl)‐flavin‐adenine dinucleotide in the active center.