The present invention relates to proteins which have an enzymatic activity for
converting -carotene into zeaxanthin or canthaxanthin into astaxanthin,
to nucleic acids which encode these proteins, to nucleic acid constructs comprising
these nucleic acids, to genetically manipulated organisms where the genetic manipulation
causes or increases the gene expression of this nucleic acid by comparison with
a wild-type, and to processes for preparing xanthophyll derivatives.