Publications

• Intermediates in the conversion of 5'-S-methylthioadenosine to methionine in Klebsiella pneumoniae.

  Furfine E.S., Abeles R.H.

  Extracts of Klebsiella pneumoniae oxidatively convert 1-phospho-5-S-methylthioribose (1-PMTR) to alpha-keto-gamma-methylthiobutyrate, a precursor of methionine, and to S-methylthiopropionate and formate. One equivalent of formate is produced per equivalent of alpha-keto-gamma-methylthiobutyrate an ... >> More

  Extracts of Klebsiella pneumoniae oxidatively convert 1-phospho-5-S-methylthioribose (1-PMTR) to alpha-keto-gamma-methylthiobutyrate, a precursor of methionine, and to S-methylthiopropionate and formate. One equivalent of formate is produced per equivalent of alpha-keto-gamma-methylthiobutyrate and two equivalents of formate per equivalent of methylthiopropionate. Two compounds were identified as intermediates in this reaction sequence: 1-phospho-5-S-methylthioribulose (1-PMT-ribulose) and 1-phospho-2,3-diketo-5-S-methylpentane. The enzyme, 1-PMTR isomerase, which converts 1-PMTR to 1-PMT-ribulose was highly purified. In addition, a protein fraction was isolated which converts 1-PMT-ribulose to the phosphodiketone. A second protein fraction was isolated that converts the phosphodiketone to an intermediate which has not been isolated so far. This intermediate is oxidatively converted to alpha-keto-gamma-methylthiobutyrate and S-methylthiopropionate by a third protein fraction. Methylthiopropionate is not derived from free alpha-keto-gamma-methylthiobutyrate. << Less

  J Biol Chem 263:9598-9606(1988) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• The methionine salvage pathway in Klebsiella pneumoniae and rat liver. Identification and characterization of two novel dioxygenases.

  Wray J.W., Abeles R.H.

  The 5-methylthio-D-ribose moiety of 5'-(methylthio)-adenosine is converted to methionine in a wide variety of organisms. 1,2-Dihydroxy-3-keto-5-methylthiopentene anion (an aci-reductone) is an advanced intermediate in the methionine salvage pathway present in the Gram-negative bacterium Klebsiella ... >> More

  The 5-methylthio-D-ribose moiety of 5'-(methylthio)-adenosine is converted to methionine in a wide variety of organisms. 1,2-Dihydroxy-3-keto-5-methylthiopentene anion (an aci-reductone) is an advanced intermediate in the methionine salvage pathway present in the Gram-negative bacterium Klebsiella pneumoniae and rat liver. This metabolite is oxidized spontaneously in air to formate and 2-keto-4-methylthiobutyric acid (the alpha-keto acid precursor of methionine). Previously, we had purified an enzyme (E2) from Klebsiella which catalyzes the oxidative degradation of the aci-reductone to formate, CO, and methylthiopropionic acid. To further characterize the reactions of the aci-reductone we used its desthio analog, 1-2-dihydroxy-3-ketohexene anion (III), which was described previously. This molecule undergoes the analogous enzymatic and non-enzymatic reactions of the natural substrate, namely the formation of formate, CO, and butyrate from III. Experiments with 18O2 show that E2 is a dioxygenase which incorporates one molecule of 18O into formate and butyric acid. No cofactor has been identified. We were unable to find an enzyme which catalyzes the conversion of 1,2-dihydroxy-3-keto-5-methylthiopentane to a keto acid precursor of methionine. The keto acid is probably produced non-enzymically in Klebsiella. We have, however, identified and purified an enzyme (E3) from rat liver, which catalyzes the formation of formate and 2-oxopentanoic acid from III. This enzyme has a monomeric molecular mass of 28,000 daltons, and no chromophoric cofactor has been identified. Experiments with 18O2 show that E3 is a dioxygenase which incorporates an 18O molecule into formate and the alpha-keto acid. In rat liver CO formation was not detected. << Less

  J Biol Chem 270:3147-3153(1995) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.