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R. C. Augusteyn, A. Ghahghaei, J. Carver; Dogfish Alpha-Crystallin. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2101.
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To determine if the properties of alpha-crystallin may have changed during the course of evolution by comparing dogfish and bovine alpha-crystallins.
Dogfish and bovine alpha-crystallins were compared using a variety of physicochemical techniques, including gel filtration, sedimentation velocity analysis, NMR spectroscopy, tryptophan fluorescence quenching, thiol reactivity and chaperone activity.
Gel filtration and sedimentation analysis indicated that dogfish alpha-crystallin is isolated as a lower molecular mass aggregate of around 400 kDa than the bovine protein (600 kDa). Probing of the environments of tryptophan and cysteine residues revealed that these residues were in very similar environments. The two proteins had very similar chaperone activities but the dogfish protein became inactive at temperatures above 80°C. Two-dimensional 1HNMR spectroscopy showed that, like the bovine protein, dogfish alpha-crystallin has a flexible C-terminal extension. However, the flexible region in the predominant alphaB subunit of the dogfish protein was longer (17 residues) than that in the bovine alphaA (10 residues) alphaB (12 residues) subunits.
Dogfish alpha-crystallins shares many properties in common with the bovine protein. It is concluded that the proteins have the same general structure and there has been little change during the ourse of evolution.
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