Pure xanthosine-n7-methyltransferase, genetically transformed coffee, pure DNA sequence that codes on expression for this transferase and method for producing caffeine free coffee beans

摘要

In the present invention, there is disclosed a substantially pure xanthosine-n7-methyltransferase, using S-adenosylmethionine as a substrate, comprising characteristic tryptic fragments A, B a C defined in Figure 4. This transferase preferably consists of an amino acid sequence as defined in Figure 6. Further disclosed is a genetically transformed coffee plant the transformation of which is based on transformation of a DNA sequence eliminating synthesis of the above-indicated transferase. Claimed is also a pure DNA sequence that codes on expression for the aforementioned transferase being selected from the group consisting of (a) a sequence as defined in Figure 5, (b) DNA sequences hybridizing to the foregoing DNA sequence specified in paragraph (a) wherein the hybridizing sequences consists of sequences that are complementary to the foregoing DNA sequence specified in paragraph (a) and c) DNA sequences that are degenerate with respect to the foregoing DNA sequences. Further claimed is a method for producing caffeine free coffee beans comprising: a) transforming coffee plants with a DNA sequence that is antisense to the DNA sequence as defined in Figure 5 as well as to a DNA sequence that codes on protein expression as defined in Figure 6 and optionally b) harvesting the fruit from the transformed coffee plant.