Interaction of Alpha-Crystallin with Sphingomyelin Membrane
Additional Funding Sources
The project described was supported by NIH Grant No. R01EY030067.
Abstract
α-crystallin, a major lens protein found on the vertebrate lens, binds to eye lens membranes progressively with age and cataract formation. A clear understanding of α-crystallin association with the eye lens membranes, particularly involving individual phospholipids (PLs), remains unknown. This study aimed to investigate the binding of α-crystallin to Sphingomyelin (SM) membrane and estimate the changes in the physical properties of the membrane after binding with α-crystallin by using Electron Paramagnetic Resonance spin-labeling method. Small unilamellar SM vesicles were prepared using the rapid solvent exchange method and incubated with α-crystallin at 37 °C for 16 hours to examine the binding of α-crystallin with SM membranes. The binding affinity (Ka) of α-crystallin to the SM membrane was estimated to be 1.49 ± 0.77 μM-1. Our results showed that the binding of α-crystallin to the SM membrane is saturable. Also, our results showed that with an increase in α-crystallin concentration, the SM membrane's mobility parameter decreases and maximum splitting increases. This indicates that as more and more α-crystallin binds to the SM membrane, it becomes more immobilized and more ordered. These results give fundamental insight into the understanding of how α-crystallin binds with the SM membrane.
Interaction of Alpha-Crystallin with Sphingomyelin Membrane
α-crystallin, a major lens protein found on the vertebrate lens, binds to eye lens membranes progressively with age and cataract formation. A clear understanding of α-crystallin association with the eye lens membranes, particularly involving individual phospholipids (PLs), remains unknown. This study aimed to investigate the binding of α-crystallin to Sphingomyelin (SM) membrane and estimate the changes in the physical properties of the membrane after binding with α-crystallin by using Electron Paramagnetic Resonance spin-labeling method. Small unilamellar SM vesicles were prepared using the rapid solvent exchange method and incubated with α-crystallin at 37 °C for 16 hours to examine the binding of α-crystallin with SM membranes. The binding affinity (Ka) of α-crystallin to the SM membrane was estimated to be 1.49 ± 0.77 μM-1. Our results showed that the binding of α-crystallin to the SM membrane is saturable. Also, our results showed that with an increase in α-crystallin concentration, the SM membrane's mobility parameter decreases and maximum splitting increases. This indicates that as more and more α-crystallin binds to the SM membrane, it becomes more immobilized and more ordered. These results give fundamental insight into the understanding of how α-crystallin binds with the SM membrane.