Alpha-Crystallin Binding with Membranes Isolated from a Single Bovine Lens Cortex

α-Crystallin binding with eye lens membranes increases with age and cataracts. This study aims to probe the α-crystallin binding with bovine cortex lens lipid (BCLL) membranes isolated from a single lens using the electron paramagnetic resonance (EPR) spin-labeling method. Small unilamellar vesicles containing 1 mol% cholestane spin label (CSL) were prepared with and without decreasing cholesterol (Chol) content in the total lipids isolated from a single bovine lens cortex. Our results show no significant binding of α-crystallin with membranes without decreased Chol content (Chol/BCLL = 0.7), but show saturable binding of α-crystallin with membranes that have decreased Chol content (Chol/BCLL = 0.1). It is likely that the decreased Chol content increases the hydrophobicity near the membrane surface, increasing the hydrophobic binding of α-crystallin with membranes. The mobility parameter of the Chol/BCLL = 0.1 membranes decreases with increased α-crystallin concentration, implying that these membranes near the surface become less mobile with α-crystallin binding. The maximum splitting of membranes does not change significantly with increased α-crystallin concentration, implying that the order of membranes near the surface does not change significantly. Our study shows the feasibility of performing these experiments using a single human lens