| MadSci Network: Biochemistry |
Hi Gonzalo!
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:
http://genomebiology.com/2005/6/5/220
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
you started.
Karin
Lin C, Todo T
The cryptochromes
Genome Biology 2005, 6:220
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