Year: 1986
Type: article
Abstract: 6-Azidoflavins have been bound to the apoproteins of five representative flavoproteins and their properties, before and after light irradiation, compared with those of the same proteins containing the appropriate 6-aminoflavin. In the dark the 6-azidoflavoproteins are quite stable, except for L-lactate oxidase, where spontaneous conversion to the 6-amino-FMN enzyme occurs slowly at pH 7. 6-Azido-FMN Old Yellow Enzyme is converted to the 6-amino-FMN enzyme by aerobic turnover with NADPH, and 6-azido-FAD D-amino acid oxidase is converted to the 6-amino-FAD enzyme by treatment with D-alanine. Light irradiation of 6-azidoriboflavin bound to riboflavin-binding protein does not result in any covalent fixation of the flavin to the protein. Light irradiation of 6-azido-FMN flavodoxin gives only a small amount of covalent linkage. In contrast, 6-azido-FMN Old Yellow Enzyme undergoes a very facile light-induced change, in which approximately 50% of the flavin is attached in a stable covalent linkage to the protein. The resulting flavoprotein form has lost the ability to bind phenols, a distinctive characteristic of the native enzyme; it does, however, bind NADPH, but the latter cannot reduce the covalently bound flavin. 6-Azido-FAD D-amino acid oxidase also undergoes a facile light modification, in which almost quantitative fixation of the flavin to the protein takes place. The resulting flavoprotein cannot bind benzoate, an active-site ligand for the native enzyme, nor is it reduced anaerobically by D-alanine. The covalent linkage is fairly labile and is destroyed on denaturation of the protein.(ABSTRACT TRUNCATED AT 250 WORDS)
Source: Biochemistry
DOI: 10.1021/bi00372a045
Authors: Vincent Massey, Sandro Ghisla, Kunio Yagi
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
Award: G2869093499
OpenAlex ID: W2140121688