METHODS FOR DETERMINING RING NUMBER IN CAROTENOIDS BY LYCOPENE EPSILON-CYCLASES AND USES THEREOF

摘要

The invention relates to methods for mapping and characterizing catalytic domains in enzymes, preferably plant enzymes and those enzymes within the carotene synthesis family and more specifically epsilon -cyclase enzymes regulating formation of epsilon , epsilon -carotene. The methods include reverse PCR and site-directed mutagenesis for generating chimera and truncations or site-directed mutations of enzymes, respectively. These chimera, truncations or site directed mutants of epsilon -cyclase enzymes are useful in the characterization of the sequence residues conferring catalytic domains for the enzymes, and more specifically, the identification of single residues regulating catalytic activity for enzymes that are important in plant growth and photosynthesis. Chimeric enzymes generated by the methods of the invention can also be used to create transgenci hosts which are augmentated in their expression of specific carotene products.