Phytoene desaturase (lycopene-forming) Phytoene desaturase (lycopene-forming) Phytoene desaturase (lycopene-forming) (CrtI, "four-step phytoene desaturase") (, "15-cis-phytoene:acceptor oxidoreductase (lycopene-forming)") are enzymes found in archaea, bacteria and fungi that are involved in carotenoid biosynthesis. They catalyze the conversion of colorless 15-"cis"-phytoene into a bright red lycopene in a biochemical pathway called the poly-trans pathway. The same process in plants and cyanobacteria utilizes four separate enzymes in a poly-cis pathway. Bacterial phytoene desaturases were shown to require FAD as a cofactor for their function. During the chemical reaction in total four additional double bonds are introduced into phytoene: In 2000 it was discovered that the gene insertion
Pigment place names remained. Historically and culturally, many famous natural pigments have been replaced with synthetic pigments, while retaining historic names. In some cases, the original color name has shifted in meaning, as a historic name has been applied to a popular modern color. By convention, a contemporary mixture of pigments that replaces a historical pigment is indicated by calling the resulting color a hue, but manufacturers are not always careful in maintaining this distinction. The following examples illustrate the shifting nature of historic pigment names: Before the development of synthetic pigments, and the refinement of techniques for extracting mineral pigments,