title: Reciprocal 13C-labeling: a method for investigating the catabolism of cosubstrates.
abstract: The principle of reciprocal labeling is to use a uniformly 13C-labeled substrate as the primary carbon source and a naturally labeled cosubstrate. Metabolites derived from a naturally labeled cosubstrate, in this case amino acids, can then be identified by their relatively lower content of 13C, and information on the degradation pathway can be deduced. The technique is based on GC-MS measurements of amino acid labeling patterns, making the technique well suited for investigating the relative importance of amino acid biosynthesis and amino acid uptake from the medium, as the 13C content of the amino acids incorporated into biomass is a direct measure of the amino acid biosyntheses. The technique is illustrated by the investigation of the degradation of phenoxyacetic acid, a medium component that is essential for production of penicillin V by Penicillium chrysogenum. Glucose was used as the uniformly labeled primary carbon source.
authors.affiliation: Center for Process Biotechnology, Department of Biotechnology, Technical University of Denmark, DK-2800 Lyngby, Denmark.
authors.forename: Bjarke
authors.initials: B
authors.lastname: Christensen
authors.forename: Jens
authors.initials: J
authors.lastname: Nielsen
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D002247:Carbon Isotopes / Q000032:analysis* / Q000378:metabolism; D005285:Fermentation; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D005947:Glucose / Q000378:metabolism*; D007553:Isotope Labeling / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008956:Models, Chemical; D010408:Penicillium chrysogenum / Q000254:growth & development / Q000378:metabolism
chemical_list: D000596:Amino Acids; D002247:Carbon Isotopes; D005947:Glucose