title: Microbial metabolism of amino alcohols. 1-Aminopropan-2-ol and ethanolamine metabolism via propionaldehyde and acetaldehyde in a species of Pseudomonas.
abstract: 1. Growth and manometric experiments showed that a Pseudomonas sp. P6 (N.C.I.B. 10431), formerly known as Achromobacter sp. P6, was capable of growth on both stereoisomers of 1-aminopropan-2-ol, and supported the hypothesis that assimilation involved metabolism to propionaldehyde, propionate and possibly 2-hydroxyglutarate. A number of alternative intermediary metabolites were ruled out. 2. Accumulation of propionaldehyde from 1-aminopropan-2-ol by intact cells occurred only during active growth, was transitory and was accompanied by morphological changes in the pseudomonad. 3. Enzymic and radioactive tracer evidence showed that 1-aminopropan-2-ol O-phosphate was the intermediate between amino alcohol and aldehyde. The operation of an inducibly formed ATP-amino alcohol phosphotransferase was established by measuring substrate disappearance, ADP formation and amino alcohol O-phosphate formation. This novel kinase had two activity peaks at about pH7 and 9. It acted on both l- and d-isomers of 1-aminopropan-2-ol, and also on l-threonine and ethanolamine, but had only low activity towards choline. The enzyme was partially purified by ion-exchange chromatography. 4. An amino alcohol O-phosphate phospho-lyase (deaminating) produced propionaldehyde from dl- and d-1-aminopropan-2-ol O-phosphate, and also formed acetaldehyde less rapidly from ethanolamine O-phosphate. It had optimum activity at about pH8 in Tris-HCl buffers. The enzyme was partially purified and evidence was obtained that a single enzyme was responsible for both activities. Apparent K(m) values for the substrates were determined. Activity was inhibited by dl-threonine O-phosphate, dl-serine O-phosphate, choline O-phosphate and P(i). Enzyme formation was induced by growth with either amino alcohol substrate. 5. Radioactive tracer experiments with dl-1-amino[3-(14)C]propan-2-ol confirmed the operation of the amino alcohol kinase and demonstrated coupling with the phospho-lyase enzyme in vitro to produce [(14)C]-propionaldehyde. 6. An aldehyde dehydrogenase, found in extracts of the pseudomonad after growth on 1-aminopropan-2-ol, was characterized and concluded to be responsible for propionaldehyde and acetaldehyde oxidation. The enzyme was inactive with methylglyoxal. 7. Propionate and acetate were concluded to be metabolized via propionyl-CoA and acetyl-CoA, and studies were made of a CoA ester synthase found in extracts. 8. Studies of a strain of Pseudomonas putida N.C.I.B. 10558 suggested that 1-aminopropan-2-ols were metabolized via their O-phosphates, propionaldehyde and propionate. Amino alcohol kinase activity was detected and extracts contained a phospho-lyase showing higher activity with the 1-aminopropan-2-ol O-phosphate than with ethanolamine O-phosphate.
mesh_terms: D000433:1-Propanol / Q000378:metabolism*; D000079:Acetaldehyde / Q000378:metabolism; D000429:Alcohol Oxidoreductases / Q000378:metabolism; D000445:Aldehyde Oxidoreductases / Q000378:metabolism; D000447:Aldehydes / Q000378:metabolism*; D000588:Amines / Q000378:metabolism*; D000605:Amino Alcohols; D002247:Carbon Isotopes; D002452:Cell Count; D002474:Cell-Free System; D002848:Chromatography, DEAE-Cellulose; D002855:Chromatography, Thin Layer; D004983:Ethanolamines / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008190:Lyases / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000378:metabolism; D010101:Oxygen Consumption; D010770:Phosphotransferases / Q000378:metabolism; D011549:Pseudomonas / Q000201:enzymology / Q000378:metabolism*; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism; D013997:Time Factors
chemical_list: D000447:Aldehydes; D000588:Amines; D000605:Amino Alcohols; D002247:Carbon Isotopes; D004983:Ethanolamines; D009943:Organophosphorus Compounds; D000433:1-Propanol; D000429:Alcohol Oxidoreductases; D000445:Aldehyde Oxidoreductases; D010770:Phosphotransferases; D008190:Lyases; D000079:Acetaldehyde