Biosynthesis of caffeine in leaves of coffee
Biosynthesis of caffeine in leaves of coffee
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DOI：
10.1104/pp.111.3.747
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发表时间：
1996-07-01
期刊：
影响因子：
7.4
通讯作者：
Crozier, A
中科院分区：
文献类型：
--
作者：
Ashihara, H;Monteiro, AM;Crozier, A
小粒咖啡芽和幼叶中内源咖啡碱和可可碱含量较高。cv肯特比在完全发育的叶。有人观察到咖啡因由C-14标记的腺嘌呤、鸟嘌呤、黄嘌呤核苷和可可碱生物合成，而其他研究（H。作者：Ashihara，A.莫里茨吉利斯，A. Crozier [1996] Planta 198：334-339）已经表明，当茶碱和黄嘌呤用作具有C.阿拉伯咖啡。咖啡因生物合成的能力，特别是从鸟嘌呤和黄嘌呤核苷，显着减少，在充分发展的成熟和老年叶。在幼叶脉冲追踪实验中获得的数据表明，AMP -> IMP ->黄苷5 '-单磷酸（或CMP ->鸟苷）->黄苷-> 7-甲基黄苷-> 7-甲基黄嘌呤->可可碱->咖啡因途径的运作。所获得的数据为反对G.M.的建议提供了强有力的证据。Nazario和C. J. Lovatt（[1993] Plant Physiol 103：1203-1210）关于咖啡因和可可碱生物合成途径的独立性以及黄嘌呤作为咖啡因生物合成中的关键中间体的作用。
The levels of endogenous caffeine and theobromine were much higher in buds and young leaves of Coffea arabica L. cv Kent than in fully developed leaves. Biosynthesis of caffeine from C-14-labeled adenine, guanine, xanthosine, and theobromine was observed, whereas other studies (H. Ashihara, A.M. Monteiro, T. Moritz, F.M. Gillies, A. Crozier [1996] Planta 198: 334-339) have indicated that there is no detectable incorporation of label into caffeine when theophylline and xanthine are used as substrates for in vivo feeds with leaves of C. arabica. The capacity for caffeine biosynthesis, especially from guanine and xanthosine, was reduced markedly in both fully developed mature and aged leaves. Data obtained in pulse-chase experiments with young leaves indicate the operation of an AMP --> IMP --> xanthosine 5'-monophosphate (or CMP --> guanosine) --> xanthosine --> 7-methylxanthosine --> 7-methylxanthine --> theobromine --> caffeine pathway. The data obtained provide strong evidence against proposals by G.M. Nazario and C.J. Lovatt ([1993] Plant Physiol 103: 1203-1210) concerning the independence of caffeine and theobromine biosynthesis pathways and the role of xanthine as a key intermediate in caffeine biosynthesis.