 The purple chromoprotein is derived from Glu-63, Tyr-64 and Gly-65 and the phenolic group of Tyr-64 plays a vital role in the formation of a conjugated system with the imidazolidone moiety resulting a high absorbance in the absorption spectrum of chromoprotein in the excited state and the replacement of Tyrosine with other amino acid leads to the alteration of optical property and non-planer properties of chromoprotein.Fluorescent proteins such as anthrozoa chromoproteins emits long wavelengths  

A single chromoprotein can act as both a phytochrome and a phototropin due to the presence and processing of multiple chromophores.Phytochrome in ferns contains PHY3 which contains an unusual photoreceptor with a dual-channel possessing both phytochrome (red-light sensing) and phototropin (blue-light sensing) and this helps the growth of fern plants at low sunlight.