Figure 13 of
Gross, Mol Vis 2000;
Figure 13. All-trans-retinol protection
Absorbance of 2 mM retinol in aqueous solution with or without protein was monitored at 330 nm at 25 °C for 1 h. Samples were incubated in total darkness (except the light beam of the spectrophotometer). The samples were not degassed, thus, they were at equilibrium with air and presumed to contain dissolved oxygen. No antioxidants or preservatives were added to the buffer. Retinol without protein (black line) apparently deteriorated rapidly as the A330 decreased by 33% in 1 h. A sample containing 1 mM EcR1 (red line, long dashes) decreased in absorbance by about 4%, while retinol mixed with 1 mM G239T (green line, shorter dashes, representing an average of three different preparations) exhibited a decrease in absorbance of about 15%. The results suggested that binding of retinol to EcR1 and G239T protected this ligand from oxidative damage [5,6]. As considered in the Discussion, G239T, because it protected retinol from damage less, appears to bind less retinol.