title: Stereospecific enzymes in the degradation of aromatic compounds by pseudomonas putida.
abstract: Two reactions in the catabolism of catechol by meta-fission, namely, hydration of 2-oxopent-4-enoate (vinylpyruvate) and aldol fission of the product, are catalyzed by stereospecific enzymes. The absolute configuration of this hydration product was shown to be l(S)-4-hydroxy-2-oxopentanoate. Vinylpyruvate hydratase, purified almost to homogeneity, had a molecular weight of about 287,000 and was dissociated in sodium dodecyl sulfate, without prior treatment with mercaptoethanol, into a species with an approximate molecular weight of 28,000. The hydratase was highly specific for its substrates; thus, although 2-oxo-cis-hex-4-enoate was also hydrated, structurally similar compounds such as the trans isomer, vinylacetic and crotonic acids, and the ring-fission products of catechol and methylcatechols were not attacked. Vinylpyruvate hydratase was activated by Mn(2+) ions. On the basis of these observations, a mechanism is proposed which closely resembles that for 4-hydroxy-2-oxopentanoate aldolase. A possible evolutionary connection between functionally related, divalent cation-activated hydro-lyases and aldolases is discussed. It was also demonstrated that l-(S)-4-hydroxy-2-oxohexanoate is the biologically active enantiomer of this hydroxy acid.
mesh_terms: D000079:Acetaldehyde / Q000096:biosynthesis; D000446:Aldehyde-Lyases / Q000302:isolation & purification / Q000378:metabolism*; D000645:Ammonium Sulfate; D002396:Catechols / Q000378:metabolism*; D011232:Chemical Precipitation; D002848:Chromatography, DEAE-Cellulose; D004591:Electrophoresis, Polyacrylamide Gel; D006358:Hot Temperature; D006836:Hydro-Lyases / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008345:Manganese / Q000494:pharmacology; D008970:Molecular Weight; D011549:Pseudomonas / Q000201:enzymology* / Q000378:metabolism; D011773:Pyruvates / Q000096:biosynthesis; D012967:Sodium Dodecyl Sulfate; D013053:Spectrophotometry; D013237:Stereoisomerism; D014631:Valerates; D014753:Vinyl Compounds
chemical_list: D002396:Catechols; D011773:Pyruvates; D014631:Valerates; D014753:Vinyl Compounds; D012967:Sodium Dodecyl Sulfate; D008345:Manganese; D000446:Aldehyde-Lyases; D006836:Hydro-Lyases; D000079:Acetaldehyde; D000645:Ammonium Sulfate