|MadSci Network: Biochemistry|
A chromophore is a portion of a molecule that is capable of absorbing light (in the visible range) and therefore dictates the color of the compound (depending on what wavelength of light it is able to absorb). In biological systems, these include hemoglobin, chlorophyll and retinal, among others. There is no specific structure of a chromophore - there are many different kinds, found in many different biological molecules. In general, though, most chromophores in biological systems contain either conjugation (alternating single and carbon double bonds) or a metal ion. Although some proteins that contain chromophores may have catalytic activities, the catalytic part would likely be separate from the chromophore portion of the protein.
Cryptochromes are a group of proteins that contain chromophores. Their
structures contain an alpha/beta domain and a helical domain, and their
chromophore is FAD (flavin adenine dinucleotide); I think some
cryptochromes may have two chromophores in them. Cryptochromes do NOT
have catalytic activity - their roles in the control of circadian rhythms
and somehow in the sensing of magnetic fields in species such as birds.
Depending on how far you have progressed through your degree, you may or
may not be able to read this review of cryptochromes:
It is very thorough, but it only focuses on the circadian rhythm side of things.
I don't know if any of this helps you, but perhaps it will at least get
Lin C, Todo T The cryptochromes Genome Biology 2005, 6:220
Try the links in the MadSci Library for more information on Biochemistry.