Studies on the mechanism of the UVA light-dependent loss of glutathione reductase activity in human lenses.

Purpose: To determine the mechanism that leads to the UVA light-dependent loss of glutathione reductase (GR) activity in human lens (HL).

Methods: Both the HL water-soluble (WS) fraction and yeast GR were irradiated with UVA light (200 mW/(cm(2). h) for 1 hour at +20 degrees C, and the specific activity (SA) was observed.

Effect of UVA light on the activity of several aged human lens enzymes.

Purpose: To determine the effect of UVA irradiation on the specific activities of several protective and metabolic enzymes in aged human lenses.

Methods: Intact human lenses (ages 55-75) in artificial aqueous humor were irradiated in a quartz cuvette with UVA light (925 J/cm(2) per hour) at +20 degrees C. The lenses were homogenized and the activities of enzymes in the water-soluble (WS) fraction were measured in irradiated and nonirradiated lenses.