Crustacyanin is a
carotenoprotein biological pigment found in the
exoskeleton of
and
and responsible for their blue colour.
β-Crustacyanin (β-CR) is composed of two stacked
astaxanthin carotenoids that absorb at λ = 580–590 nm (2.10–2.14 eV).
α-crustacyanin (α-CR) is an assembly of eight β-CR
. It is a 320 kDa (atomic mass) complex containing 16 astaxanthin molecules.
Although the β-CR dimer has a peak wavelength of 580 nm, α-CR exhibits a bathochromic shift to 632 nm; the mechanism and function of the additional wavelength shift is not understood.
