Nature 302, 415 - 417 (31 March 1983); doi:10.1038/302415a0

Short-range order of crystallin proteins accounts for eye lens transparency

Mireille Delaye^* & Annette Tardieu^†

^*Laboratoire de Physique des Solides, Bat. 510, Université Paris-Sud, 91405 Orsay, France
^†Centre de Génétique Moléculaire, CNRS, 91190 Gif-sur-Yvette, France

In its normal state, the eye lens is transparent despite the presence in the cell cytoplasm of high concentrations of proteins, the crystalline, which, a priori, could be expected to scatter an important part of the incident light. Early on, an explanation was sought in the spatial correlations between individual scatterers. Trokel¹ first proposed that the "high concentration of proteins in the lens must be accompanied by a degree of local order approaching a paracrystalline state"; Benedek² subsequently suggested that a dense, noncrystalline packing of the proteins would sufficiently reduce the scattered intensity. However, in spite of an improved understanding of the molecular structure of crystallins³⁻⁶, their spatial order remained unknown. We present here a small-angle X-ray scattering study of the problem, performed with calf lens cytoplasm both in intact lenses and in cytoplasmic extracts where the crystallin concentration was varied from 3 to 510 mg ml^-1. All our experimental data are consistent with short-range spatial order, as in dense liquids or glasses⁷⁻⁹, and this provides a simple explanation for lens transparency^2,10. In addition, we detected no conformational change or reorganization of the crystallin proteins throughout the investigated concentration range.

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