Abstract
Purpose :
To investigate the association of α-crystallin with membranes prepared from total lipids isolated from a single bovine eye lens, measure the physical properties of membranes, and illustrate the feasibility that such experiments can be conducted for membranes prepared from total lipids isolated from a single human eye lens.
Methods :
Small unilamellar vesicles were prepared with and without decreasing the cholesterol (Chol) content from total lipids isolated from a single lens cortex of two-year-old bovine using the rapid solvent exchange method and probe-tip sonication. Chol content in the cortical membranes was decreased by adding lipid (phospholipids and sphingolipid) mixtures resembling bovine lens lipid composition. The electron paramagnetic resonance spin-labeling method was used to measure the percentage of membrane surface occupied (MSO) by α-crystallin, the association constant (Ka), and the physical properties (hydrophobicity, mobility parameter, and maximum splitting) of membranes.
Results :
No association of α-crystallin with bovine lens lipid membranes derived from the single-lens cortex was observed. However, α-crystallin association with cortical membranes with reduced Chol content was observed. The smaller the Chol content in cortical membranes, the larger the MSO and Ka, and vice-versa. These results imply that the membrane Chol is a key component in preventing α-crystallin association with the bovine lens lipid membrane. Hydrophobicity near the surface of cortical membranes increased with the increased α-crystallin association, supporting the hypothesis that α-crystallin association with lens membranes forms a barrier to polar molecules. The profiles of mobility parameters decreased and maximum splitting showed no significant change with the increased α-crystallin concentration, indicating that cortical membranes became less mobile with no significant change in order near the surface with the α-crystallin association.
Conclusions :
Results show that the membrane Chol plays a crucial role in inhibiting α-crystallin association with the bovine lens lipid membrane, and such association alters the physical properties of membranes playing a vital role in modulating the integrity of membranes. Moreover, this study demonstrates that it is feasible to investigate the association of α-crystallin with membranes derived from a single human lens.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.