title: Si-face stereospecificity at C5 of coenzyme F420 for F420-dependent glucose-6-phosphate dehydrogenase from Mycobacterium smegmatis and F420-dependent alcohol dehydrogenase from Methanoculleus thermophilicus.
abstract: Coenzyme F420 is a 5-deazaflavin. Upon reduction, 1,5-dihydro-coenzyme F420 is formed with a prochiral center at C5. In this study we report that the F420-dependent glucose-6-phosphate dehydrogenase from Mycobacterium smegmatis and the F420-dependent alcohol dehydrogenase from Methanoculleus thermophilicus are Si-face stereospecific with respect to C5 of the 5-deazaflavin. These results were obtained by following the stereochemical course of the reversible incorporation of 3H into F420 from tritium-labeled substrates. Our findings bring to eight the number of coenzyme-F420-dependent enzymes shown to be Si-face stereospecific. No F420-dependent enzyme with Re-face stereospecificity is known. This is noteworthy since coenzyme F420 is functionally similar to pyridine nucleotides for which both Si-face and Re-face specific enzymes have been found.
authors.affiliation: Max-Planck-Institut für terrestrische Mikrobiologie, Philipps-Universität, Marburg, Germany.
authors.forename: A R
authors.initials: AR
authors.lastname: Klein
authors.forename: H
authors.initials: H
authors.lastname: Berk
authors.forename: E
authors.initials: E
authors.lastname: Purwantini
authors.forename: L
authors.initials: L
authors.lastname: Daniels
authors.forename: R K
authors.initials: RK
authors.lastname: Thauer
mesh_terms: D000426:Alcohol Dehydrogenase / Q000378:metabolism*; D002384:Catalysis; D019605:Euryarchaeota / Q000201:enzymology*; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism*; D009161:Mycobacterium / Q000201:enzymology*; D012256:Riboflavin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D013237:Stereoisomerism
chemical_list: C015084:coenzyme F420; D000426:Alcohol Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D012256:Riboflavin