RT Journal Article SR Electronic(1) A1 McCready, Kevin A. A1 Ratledge, ColinYR 1979 T1 Ferrimycobactin Reductase Activity from Mycobacterium smegmatis JF Microbiology, VO 113 IS 1 SP 67 OP 72 DO https://doi.org/10.1099/00221287-113-1-67 PB Microbiology Society, SN 1465-2080, AB Ferrimycobactin reductase activity from Mycobacterium smegmatis grown under iron-deficient conditions had a K m for ferrimycobactin of less than 4 μm and a K m for NADH of 1·75 mm. Salicylate (0·12 mm), which is synthesized by this bacterium, could substitute for EDTA as an acceptor of Fe2+ in the assay system. Reagents which react with thiol groups (HgCl2, N-ethylmaleimide) at 0·1 mm inhibited activity by about 40%; other inhibitors (KCN, NaN3, carbonyl cyanide m-chlorophenylhydrazone and 2,4-dinitrophenol) were less effective (though these inhibited active iron transport, which uses exochelin and not mycobactin; Stephenson & Ratledge, 1979 ). The rate of ferrimycobactin reduction in extracts was about ten times faster than the rate observed in vivo following a shift-up of low-iron cells to high-iron status. Reduction of iron in ferri-ferrioxamine B, ferriexochelin MS and ferric ammonium citrate occurred at comparable rates to ferrimycobactin reduction. Ferrimycobactin reductase activity was undiminished in M. smegmatis grown under iron-sufficient conditions. A similar activity was found in extracts of Escherichia coli and Candida utilis where it still required NADH. Yeast alcohol dehydrogenase reduced ferrimycobactin independently of NADH; this activity was attributed to the free thiol groups of this protein. Reductase activity therefore may be associated with a protein whose principal function need not be that of a siderophore reductase., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-113-1-67