beta/gamma-Crystallins are predominant structural proteins in vertebrate lens with unique properties of extremely high solubility, long-term stability and resistance to UV damage. Four conserved Trp residues in beta/gamma-crystallins account for UV absorbance and thereafter fluorescence quenching to avoid photo damage. Herein we found that beta B2-crystallin Trp fluorescence was greatly enhanced by the introduction of an extra unquenched Trp fluorophore by cataract-associated mutations S31W and R145W. Both mutations impaired oligomerization, decreased stability and promote thermal aggregation, while S31W was more deleterious. S31W accelerated beta B2-crystallin aggregation under UV damaging conditions, whereas R145W delayed. These observations suggested that the introduction of an extra Trp fluorophore had complicated effects on beta B2-crystallin stability and aggregation against various stresses. Our findings highlight that the number of Trp fluorophores in beta/gamma-crystallin is evolutionarily optimized to exquisitely perform their structural roles in the lens. (C) 2018 Elsevier Inc. All rights reserved.