Photobleachable fluorescent species in wool keratin

Abstract

The fluorescence from scoured merino wool was examined systematically using excitation wavelengths ranging from 280 to 400 nm. Absorption maxima of various fluorophores, were identified. Irradiation of dry wool in dry air at 325 nm selectively destroyed or bleached the fluorophore absorbing maximally at 335 nm while irradiation of dry wool at 365 nm bleached the two fluorophores absorbing maximally at 335 and 380 nm. Comparison of the fluorescence from wool with that observed from collagen by excitation with UVA radiation suggests that the fluorophores present in wool absorbing above 350 nm are not tyrosine derivatives and are probably tryptophan oxidation or hydrolysis products.