caa a22 4500 477100767 CHVBK 20180405111540.0 cr unu---uuuuu 170330e19960901xx s 000 0 eng 10.1007/BF00620048 doi (NATIONALLICENCE)springer-10.1007/BF00620048 Catabolism of caffeine and related purine alkaloids in leaves of Coffea arabica L [Elektronische Daten] [H. Ashihara, A. Monteiro, T. Moritz, F. Gillies, A. Crozier] In a study of purine alkaloid catabolism pathways in coffee,14C-labelled theobromine, caffeine, theophylline and xanthine were incubated with leaves ofCoffea arabica. Incorporation of label into14CO2 was determined and methanol-soluble metabolites were analysed by high-performance liquid chromatography-radiocounting. The data obtained demonstrate catabolism of caffeine → theophylline → 3-methylxanthine → xanthine. Xanthine is degraded further by the conventional purine catabolism pathway to CO2 and NH3 via uric acid, allantoin and allantoic acid. The conversion of caffeine to theophylline is the rate-limiting step in purine alkaloid catabolism and provides a ready explanation for the high concentration of endogenous caffeine found inC. arabica leaves. Although theobromine is converted primarily to caffeine, a small portion of the theobromine pool appears to be degraded to xanthine by a caffeine-independent pathway. In addition to being broken down to CO2, via the purine catabolism pathway, xanthine is metabolised to 7-methylxanthine. Metabolism of [2-14C]xanthine byC. arabica leaves in the presence of 5 mM allopurinol results in very large increases in incorporation of radioactivity into 7-methylxanthine as degradation of the substrate via the purine catabolism pathway is blocked. The identity of 7-methylxanthine in these studies was confirmed by gas chromatography-mass spectrometry analysis. Springer-Verlag, 1996 Caffeine nationallicence Catabolism pathways nationallicence Coffea nationallicence Purine alkaloids nationallicence HPLC-RC : high-performance liquid chromatography-radiocounting nationallicence Ashihara H. Department of Biology, Faculty of Science, Ochanomizu University, Otsuka, Bunkyo-ku, 112, Tokyo, Japan aut Monteiro A. Bower Building, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, G12 8QQ, Glasgow, UK aut Moritz T. Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S-90183, Umeä, Sweden aut Gillies F. Bower Building, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, G12 8QQ, Glasgow, UK aut Crozier A. Bower Building, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, G12 8QQ, Glasgow, UK aut Planta Springer-Verlag 198/3(1996-09-01), 334-339 0032-0935 198:3<334 1996 198 425 https://doi.org/10.1007/BF00620048 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00620048 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ashihara H. Department of Biology, Faculty of Science, Ochanomizu University, Otsuka, Bunkyo-ku, 112, Tokyo, Japan aut NATIONALLICENCE 700 1- Monteiro A. Bower Building, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, G12 8QQ, Glasgow, UK aut NATIONALLICENCE 700 1- Moritz T. Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S-90183, Umeä, Sweden aut NATIONALLICENCE 700 1- Gillies F. Bower Building, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, G12 8QQ, Glasgow, UK aut NATIONALLICENCE 700 1- Crozier A. Bower Building, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, G12 8QQ, Glasgow, UK aut NATIONALLICENCE 773 0- Planta Springer-Verlag 198/3(1996-09-01), 334-339 0032-0935 198:3<334 1996 198 425 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer