Intermediates in the conversion of 5'-S-methylthioadenosine to methionine in Klebsiella pneumoniae.
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.
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Graduate Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02254.
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D000241:Adenosine / Q000031:analogs & derivatives* / Q000378:metabolism; D019747:Aldose-Ketose Isomerases; D000818:Animals; D002238:Carbohydrate Epimerases / Q000302:isolation & purification / Q000378:metabolism; D055598:Chemical Phenomena; D002621:Chemistry; D002851:Chromatography, High Pressure Liquid; D003839:Deoxyadenosines; D005561:Formates / Q000378:metabolism; D007711:Klebsiella pneumoniae / Q000378:metabolism*; D008099:Liver / Q000201:enzymology; D009682:Magnetic Resonance Spectroscopy; D008715:Methionine / Q000378:metabolism*; D009943:Organophosphorus Compounds / Q000378:metabolism; D010084:Oxidation-Reduction; D010504:Periodic Acid; D051381:Rats; D012267:Ribosemonophosphates / Q000378:metabolism; D013865:Thioglycosides / Q000378:metabolism; D013872:Thionucleosides / Q000378:metabolism*
C023029:5'-methylthioribose 1-phosphate; D003839:Deoxyadenosines; D005561:Formates; D009943:Organophosphorus Compounds; D012267:Ribosemonophosphates; D013865:Thioglycosides; D013872:Thionucleosides; C030544:formic acid; D010504:Periodic Acid; C056456:1-phospho-2,3-diketo-5-S-methylthiopentane; C008500:5'-methylthioadenosine; D008715:Methionine; C009288:metaperiodate; D002238:Carbohydrate Epimerases; C056455:1-phospho-5-S-methylthioribofuranoside isomerase; D019747:Aldose-Ketose Isomerases; D000241:Adenosine