Thermal stability of UV-irradiated collagen in bovine lens capsules and in bovine cornea

The irradiation of lens capsules with UVB light in vitro resulted in changes in the thermal properties of type-IV collagen consistent with increased cross-linking. DSC of lens capsules showed two major peaks at melting temperatures at 54 °C (Tm1) and 78 °C (Tm2), which can be attributed to the denaturation of the triple helix and 7S domains, respectively. UVB irradiation of lens capsules in vitro for 6 h caused an increase in Tm1 from 54 to 57 °C. The higher temperature required to denature the type-IV collagen after irradiation in vitro suggested an increase of intermolecular cross-linking.