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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1996 Jan 9;93(1):377–382. doi: 10.1073/pnas.93.1.377

Phase separation in aqueous solutions of lens gamma-crystallins: special role of gamma s.

C Liu 1, N Asherie 1, A Lomakin 1, J Pande 1, O Ogun 1, G B Benedek 1
PMCID: PMC40241  PMID: 8552642

Abstract

We have studied liquid-liquid phase separation in aqueous ternary solutions of calf lens gamma-crystallin proteins. Specifically, we have examined two ternary systems containing gamma s--namely, gamma IVa with gamma s in water and gamma II with gamma s in water. For each system, the phase-separation temperatures (Tph (phi)) alpha as a function of the overall protein volume fraction phi at various fixed compositions alpha (the "cloud-point curves") were measured. For the gamma IVa, gamma s, and water ternary solution, a binodal curve composed of pairs of coexisting points, (phi I, alpha 1) and (phi II, alpha II), at a fixed temperature (20 degrees C) was also determined. We observe that on the cloud-point curve the critical point is at a higher volume fraction than the maximum phase-separation temperature point. We also find that typically the difference in composition between the coexisting phases is at least as significant as the difference in volume fraction. We show that the asymmetric shape of the cloud-point curve is a consequence of this significant composition difference. Our observation that the phase-separation temperature of the mixtures in the high volume fraction region is strongly suppressed suggests that gamma s-crystallin may play an important role in maintaining the transparency of the lens.

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Selected References

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  1. Benedek G. B. The molecular basis of cataract formation. Ciba Found Symp. 1984;106:237–247. doi: 10.1002/9780470720875.ch14. [DOI] [PubMed] [Google Scholar]
  2. Berland C. R., Thurston G. M., Kondo M., Broide M. L., Pande J., Ogun O., Benedek G. B. Solid-liquid phase boundaries of lens protein solutions. Proc Natl Acad Sci U S A. 1992 Feb 15;89(4):1214–1218. doi: 10.1073/pnas.89.4.1214. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Broide M. L., Berland C. R., Pande J., Ogun O. O., Benedek G. B. Binary-liquid phase separation of lens protein solutions. Proc Natl Acad Sci U S A. 1991 Jul 1;88(13):5660–5664. doi: 10.1073/pnas.88.13.5660. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Nagineni C. N., Bhat S. P. Lens fiber cell differentiation and expression of crystallins in co-cultures of human fetal lens epithelial cells and fibroblasts. Exp Eye Res. 1992 Feb;54(2):193–200. doi: 10.1016/s0014-4835(05)80208-8. [DOI] [PubMed] [Google Scholar]
  5. Pande J., Lomakin A., Fine B., Ogun O., Sokolinski I., Benedek G. Oxidation of gamma II-crystallin solutions yields dimers with a high phase separation temperature. Proc Natl Acad Sci U S A. 1995 Feb 14;92(4):1067–1071. doi: 10.1073/pnas.92.4.1067. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Schurtenberger P, Chamberlin RA, Thurston GM, Thomson JA, Benedek GB. Observation of critical phenomena in a protein-water solution. Phys Rev Lett. 1989 Nov 6;63(19):2064–2067. doi: 10.1103/PhysRevLett.63.2064. [DOI] [PubMed] [Google Scholar]
  7. Siezen R. J., Fisch M. R., Slingsby C., Benedek G. B. Opacification of gamma-crystallin solutions from calf lens in relation to cold cataract formation. Proc Natl Acad Sci U S A. 1985 Mar;82(6):1701–1705. doi: 10.1073/pnas.82.6.1701. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Siezen R. J., Kaplan E. D., Anello R. D. Superior resolution of gamma-crystallins from microdissected eye lens by cation-exchange high-performance liquid chromatography. Biochem Biophys Res Commun. 1985 Feb 28;127(1):153–160. doi: 10.1016/s0006-291x(85)80138-8. [DOI] [PubMed] [Google Scholar]
  9. Tardieu A., Vérétout F., Krop B., Slingsby C. Protein interactions in the calf eye lens: interactions between beta-crystallins are repulsive whereas in gamma-crystallins they are attractive. Eur Biophys J. 1992;21(1):1–12. doi: 10.1007/BF00195438. [DOI] [PubMed] [Google Scholar]
  10. Thomson J. A., Schurtenberger P., Thurston G. M., Benedek G. B. Binary liquid phase separation and critical phenomena in a protein/water solution. Proc Natl Acad Sci U S A. 1987 Oct;84(20):7079–7083. doi: 10.1073/pnas.84.20.7079. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Wistow G. J., Piatigorsky J. Lens crystallins: the evolution and expression of proteins for a highly specialized tissue. Annu Rev Biochem. 1988;57:479–504. doi: 10.1146/annurev.bi.57.070188.002403. [DOI] [PubMed] [Google Scholar]
  12. Zigler J. S., Jr, Horwitz J., Kinoshita J. H. Studies on the low molecular weight proteins of human lens. Exp Eye Res. 1981 Jan;32(1):21–30. doi: 10.1016/s0014-4835(81)80035-8. [DOI] [PubMed] [Google Scholar]
  13. van Dam A. F. Purification and composition of beta-s-crystallin. Exp Eye Res. 1966 Oct;5(4):255–266. doi: 10.1016/s0014-4835(66)80035-0. [DOI] [PubMed] [Google Scholar]

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