title: Alpha-crystallin exists in a non-spherical form. A study on the rotational properties of native and reconstituted alpha-crystallin.
abstract: Native alpha-crystallin, obtained from the cortex of calf lenses with FPLC (Pharmacia) was characterized by means of transient-electric-birefringence measurements and ultraviolet linear-dichroism spectroscopy. These techniques were also performed on 6-M-urea-dissociated and reconstituted alpha-crystallin. Transient-electric-birefringence measurements offer the possibility to characterize the often observed, but usually neglected, non-spherical occurrences of alpha-crystallin in more detail. Although not distinguishable with size-exclusion chromatography, we could identify at least two different classes of both native and reconstituted alpha-crystallin, from which at least one consists of non-spherical molecules. The results are compared with those obtained with electron microscopy using different staining methods. From the three independent techniques used we find evidence that a fraction of the alpha-crystallin exists in a more extended quaternary structure. The results are difficult to explain with a concentric three-layer model for alpha-crystallin as proposed by Tardieu et al. [Tardieu, A., Laporte, D., Licinio, P., Krop, B. & Delaye, M. (1986) J. Mol. Biol. 192, 711-724].
authors.affiliation: Dept. of Biophysics, Free University, Amsterdam, The Netherlands.
authors.forename: B
authors.initials: B
authors.lastname: van Haeringen
authors.forename: D
authors.initials: D
authors.lastname: Eden
authors.forename: M R
authors.initials: MR
authors.lastname: van den Bogaerde
authors.forename: R
authors.initials: R
authors.lastname: van Grondelle
authors.forename: M
authors.initials: M
authors.lastname: Bloemendal
mesh_terms: D000818:Animals; D002417:Cattle; D002853:Chromatography, Liquid; D003459:Crystallins / Q000737:chemistry*; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet
chemical_list: D003459:Crystallins