Virginia TechSusanti, DwiLoganathan, Usha R.Compton, AustinMukhopadhyay, Biswarup2017-12-062017-12-062017-08-03http://hdl.handle.net/10919/81058Flavin-containing Trx reductase (TrxR) of Thermoplasma acidophilum (Ta), a thermoacidophilic facultative anaerobic archaeon, lacks the structural features for the binding of 2′-phosphate of nicotinamide adenine dinucleotide phosphate (NADPH), and this feature has justified the observed lack of activity with NADPH; NADH has also been reported to be ineffective. Our recent phylogenetic analysis identified Ta-TrxR as closely related to the NADHdependent enzymes of Thermotoga maritima and Desulfovibrio vulgaris, both being anaerobic bacteria. This observation instigated a reexamination of the activity of the enzyme, which showed that Ta-TrxR is NADH dependent; the apparent Km for NADH was 3.1 μM, a physiologically relevant value. This finding is consistent with the observation that NADH:TrxR has thus far been found primarily in anaerobic bacteria and archaea.application/pdfenCreative Commons Attribution-NonCommercial 4.0 InternationalArticle - Refereedhttps://doi.org/10.1021/acsomega.7b006402