2-HYDROXYISONICOTINATE DEHYDROGENASE ISOLATED FROM MYCOBACTERIUM SP. INA1

2-Hydroxyisonicotinate dehydrogenase from Mycobacterium sp. INA1 was p urified 26-fold to apparent homogeneity. The enzyme is involved in iso nicotinate degradation by Mycobacterium sp. INA1 and catalyzes the con version of 2-hydroxyisonicotinate to 2,6-dihydroxypyridine-4-carboxyla te. The purified protein exhibited a native molecular mass of 300 kDa and subunits of 97, 31 and 17 kDa, respectively, indicating an alpha(2 )beta(2)gamma(2) structure. The absorption spectrum of the homogeneous enzyme was characteristic for an iron/sulfur flavoprotein. 3.8 mol of iron, 3.7 mol of acid labile sulfur, 0.94 mol of FAD and 0.75 mol of molybdenum were determined per mol of protomer. The molybdenum cofacto r was identified as molybdopterin cytosine dinucleotide. 2-Hydroxyison icotinate dehydrogenase was inactivated in the presence of cyanide. Ac cording to these basic properties the protein seems to belong to the c lass of molybdo-iron/sulfur flavoproteins of the xanthine oxidase fami ly. (C) 1998 Federation of European Microbiological Societies. Publish ed by Elsevier Science B.V. All rights reserved.