This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
|Superclasses:||Degradation/Utilization/Assimilation → Secondary Metabolites Degradation → Nitrogen Containing Secondary Compounds Degradation → Alkaloids Degradation → Caffeine Degradation|
Caffeine is found in several plant species including coffea, tea and cacao. The contents of caffeine vary greatly from cultivar to cultivar, tissue to tissue, and from different developmental stages. One mechanism that plants use to control caffeine level is by balancing between caffeine biosynthesis and degradation. The main caffeine degradation pathway has been proposed to proceed via theophylline and 3-methylxanthine, which is depicted here. In addition to the main caffeine degradation pathway, minor plant species-specific degradation pathways have also been proposed. All the proposed pathways were based on radio-tracer studies (reviewed in [Ashihara08, Mazzafera04]). No enzyme activity has been detected or characterized to date.
About This Pathway
In this main caffeine degradation pathway, caffeine is degraded by sequential removal of the three methyl groups, resulting in the formation of xanthine. Xanthine is further degraded to CO2 and NH3 via purine degradation ( purine nucleotides degradation I (plants)). C14 labeled theophylline was degraded to CO2 far more rapidly than C14 labeled caffeine, indicating the first step of the pathway is the rate-limiting step [Ito97].
Variants: caffeine degradation II, caffeine degradation III (bacteria, via demethylation), caffeine degradation IV (bacteria, via demethylation and oxidation), caffeine degradation V (bacteria, via trimethylurate)
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