Physicochemical studies on bovine eye lens proteins II. Comparative physical study of the low-molecular-weight α-crystallins from calf lens cortical and nuclear fiber cells

Abstract

The α L of cortical and nuclear fiber cells have been studied using hydrodynamical and physicochemical techniques. From the sedimentation and the diffusion coefficients in identical conditions, it can be concluded that α L, N is appreciably larger than α L, C but both have a similar structure in solution: a spherical particle with a high hydration. The α L, N not only contains several degraded αA- and αB-peptides but also a typical pattern of β-peptides. The fluorescence spectrum indicates a shift of the hydrophobic tryptophan residues from a hydrophobic environment in α L, C to a more solvent-exposed and polar neighbourhood for α L, N. Also solubility studies on α L, C and α L, N in different solvent conditions and temperatures, indicate more apolar interactions between the peptides of the nuclear α L, than its cortical counterpart. The more hydrophobic interaction pattern of the peptides in α L, N can also be reconciled with a lower mean hydration potential, indicative of a higher hydrophobicity of the degraded αA-peptides.