Please use this identifier to cite or link to this item: https://repositorio.inpa.gov.br/handle/1/17738
Title: Molecular and biochemical characterization of caffeine synthase and purine alkaloid concentration in guarana fruit
Authors: Schimpl, Flávia Camila
Kiyota, Eduardo
Mayer, Juliana Lischka Sampaio
Gonçalves, José Francisco de Carvalho
Silva, José Ferreira da
Mazzafera, Paulo
Keywords: Paullinia Cupana
Sapindaceae
Theobroma Cacao
7-methylxanthine
Alkaloid
Caffeine
Caffeine Synthase
Methyltransferase
Purine
Purine Derivative
Theobromine
Theophylline
Xanthine Derivative
Amino Acid Sequence
Chemical Structure
Chemistry
Enzymology
Fruit
Genetics
Isolation And Purification
Metabolism
Methylation
Nucleotide Sequence
Paullinia
Plant Leaf
Seed Plant
Alkaloids
Amino Acid Sequence
Base Sequence
Caffeine
Fruit
Methylation
Methyltransferases
Molecular Structure
Paullinia
Plant Leaves
Purines
Seeds
Theobromine
Theophylline
Xanthines
Issue Date: 2014
metadata.dc.publisher.journal: Phytochemistry
metadata.dc.relation.ispartof: Volume 105, Pags. 25-36
Abstract: Guarana seeds have the highest caffeine concentration among plants accumulating purine alkaloids, but in contrast with coffee and tea, practically nothing is known about caffeine metabolism in this Amazonian plant. In this study, the levels of purine alkaloids in tissues of five guarana cultivars were determined. Theobromine was the main alkaloid that accumulated in leaves, stems, inflorescences and pericarps of fruit, while caffeine accumulated in the seeds and reached levels from 3.3% to 5.8%. In all tissues analysed, the alkaloid concentration, whether theobromine or caffeine, was higher in young/immature tissues, then decreasing with plant development/maturation. Caffeine synthase activity was highest in seeds of immature fruit. A nucleotide sequence (PcCS) was assembled with sequences retrieved from the EST database REALGENE using sequences of caffeine synthase from coffee and tea, whose expression was also highest in seeds from immature fruit. The PcCS has 1083 bp and the protein sequence has greater similarity and identity with the caffeine synthase from cocoa (BTS1) and tea (TCS1). A recombinant PcCS allowed functional characterization of the enzyme as a bifunctional CS, able to catalyse the methylation of 7-methylxanthine to theobromine (3,7-dimethylxanthine), and theobromine to caffeine (1,3,7-trimethylxanthine), respectively. Among several substrates tested, PcCS showed higher affinity for theobromine, differing from all other caffeine synthases described so far, which have higher affinity for paraxanthine. When compared to previous knowledge on the protein structure of coffee caffeine synthase, the unique substrate affinity of PcCS is probably explained by the amino acid residues found in the active site of the predicted protein. © 2014 Elsevier Ltd. All rights reserved.
metadata.dc.identifier.doi: 10.1016/j.phytochem.2014.04.018
Appears in Collections:Artigos

Files in This Item:
There are no files associated with this item.


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.