The generation of @entity273 by the UVA irradiation of XXXX lens proteins.

@entity1 @entity1522 @entity274 @entity231 @entity3793 @entity535 @entity26 @entity2097 @entity2340 @entity273 @entity599 @entity224
The water-insoluble proteins from aged @entity1 lens are known to contain protein-bound chromophores that act as UVA senisitizers. The irradiation of a sonication-solubilized, water-insoluble fraction from @entity1 lenses (55-75 years) with UVA light (1.5 kJ/cm2, gamma > 338nm) caused an @entity26 -dependent photolysis of @entity2340 , not seen when either alpha-crystallin or lysozyme were irradiated. The suggested requirement for active @entity26 species was consistent with a linear increase in @entity273 formation, which was also observed. A final concentration of 55 microM @entity274 was attained, with no @entity274 being detected in either dark-incubated controls or in irradiated samples of native proteins. The UVA-dependent @entity274 formation was increased 50% by @entity224 dismutase (SOD) and abolished by catalase, arguing for the initial generation of @entity224 anion. A linear photolysis of @entity3793 and @entity2340 was also seen; however, the addition of SOD or SOD and catalase had no effect on the photolytic destruction of either @entity535 . @entity224 dismutase increased the oxidation of protein SH groups implicating @entity274 , but SOD and catalase caused a decrease in SH oxidation only at later time periods. The direct addition of @entity274 to a water-insoluble sonicate supernatant fraction caused only a slight oxidation of SH groups, but this was increased four- to eight-fold when the protein was denatured in 4.0 M @entity2097 . Overall, the data suggest a UVA-dependent oxidation of protein SH groups via @entity274 generated within the large protein aggregates of the water-insoluble fraction. These data also provide a mechanism for oxidation of the @entity599 -containing @entity1522 in vivo--a process that is known to accompany the formation of age-onset @entity231 .
