TAILIEUCHUNG - Báo cáo khoa học: In situ proton NMR analysis of a-alkynoate biotransformations

Only 2% of the known natural products with acetylenic bonds area-alkynoates. Their polarized, conjugated triple bond is an optimal target for an enzymic hydration. Therefore they are good substrates for the enzymes involved in metabolism of acetylenic compounds, resulting in products that are suitable for bacterial growth. We isolated a Pseudomonas putida strain growing on 2-butynedioate as well as on propynoate, and determined the metabolic pathways of these two a-alkynoates. | Eur. J. Biochem. 270 1393-1398 2003 FEBS 2003 doi In situ proton NMR analysis of a-alkynoate biotransformations From invisible substrates to detectable metabolites Lothar Brecker1 I Julia Petschnigg1 Nicole Depine1 Hansjorg Weber1 and Douglas W. Ribbons1 2 1 Institute of Organic Chemistry University of Technology Graz Austria 2Institute of Biotechnology University of Technology Graz Austria Only 2 of the known natural products with acetylenic bonds are a-alkynoates. Their polarized conjugated triple bond is an optimal target for an enzymic hydration. Therefore they are good substrates for the enzymes involved in metabolism of acetylenic compounds resulting in products that are suitable for bacterial growth. We isolated a Pseudomonas putida strain growing on 2-butynedioate as well as on propynoate and determined the metabolic pathways of these two a-alkynoates. The triple bonds in both compounds were initially hydrated and 2-ketobutandioate as well as 3-ketopropanoate were formed. These two b-keto acids were decarboxylated resulting in pyruvate and acetaldehyde respectively. Pyruvate was further hydrolysed mainly to acetate and formate whereas minor amounts were reduced to lactate. In the other biotransformation acetaldehyde was oxidized to acetate accompanied by the reduction of 3-ketopro-panoate to 3-hydroxypropanoate. Analyses of these metabolic processes were performed by in situ H-NMR spectroscopy in 1H2O although the substrates propynoate and 2-butynedioate carried only one or even no detectable protons respectively. However while protons from the solvent are incorporated in the course of the pathway the metabolites can be detected and identified. Therefore a detailed determination of the metabolic process is possible. Keywords 2-butynedioate in situ 1H-NMR Pseudomonas putida propynoate triple bond. Acetylenic bonds are quite rare in natural compounds compared with vinyl bonds carbonyl groups carboxylates or aromatic rings but

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