Stereospecific Enzymes in the Degradation of Aromatic Compounds by Pseudomonas putida

AUTOR(ES)

Collinsworth, William L.

RESUMO

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 Mn2+ 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.

Documentos Relacionados

• Regulation of the pcaIJ genes for aromatic acid degradation in Pseudomonas putida.
• Separation of d-(+)-Nicotine from a Racemic Mixture by Stereospecific Degradation of the l-(−) Isomer with Pseudomonas putida
• Induction Specificity and Catabolite Repression of the Early Enzymes in Camphor Degradation by Pseudomonas putida
• Stable Isotope Fractionation Caused by Glycyl Radical Enzymes during Bacterial Degradation of Aromatic Compounds
• Addition of Aromatic Substrates Restores Trichloroethylene Degradation Activity in Pseudomonas putida F1