The increasing demand for decaffeinated coffee and tea has resulted from the occasional side effects of caffeine, which include palpitations, gastrointestinal disturbances, anxiety, tremor, increased blood pressure and insomnia1, 2. At present, the decaffeination process depends on supercritical fluid extraction with carbon dioxide to avoid introducing toxic residues from extraction solvents. However, this operation is expensive and, to discerning customers, flavours and aromas are lost. There are some Coffea and Camellia species that produce low levels of caffeine, but these are not readily available for commercial use. Although it might be feasible to develop a breeding programme, it could take 20 years or so to establish and stabilize the desired traits3.
Caffeine is synthesized from purine nucleotides.
It has been hard to purify and isolate caffeine synthase and other enzymes of this pathway because they are extremely labile, but the amino-terminal sequence of caffeine synthase from young tea leaves has now been reported5. To determine whether our cDNA encoded an active caffeine synthase enzyme, we expressed TCS1 in Escherichia coli and incubated lysates of the bacterial cells with a variety of xanthine substrates in the presence of S-adenosylmethionine as methyl donor. These results indicate that TCS1 encodes caffeine synthase. The cloning of the caffeine synthase gene is an important advance towards the development of transgenic caffeine- deficient Camellia sinensis and Coffea arabica plants through antisense messenger RNA technology or by gene silencing. Kato, M. et al.