Oxidation of gamma II-crystallin solutions yields dimers with a high phase separation temperature
| Autor: | Bernard M. Fine, I. Sokolinski, Aleksey Lomakin, Jayanti Pande, Olutayo Ogun, George B. Benedek |
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| Rok vydání: | 1995 |
| Předmět: |
chemistry.chemical_classification
Multidisciplinary Aqueous solution Molecular mass Reducing agent Chemistry Dimer Temperature Protein aggregation Crystallins Dithiothreitol Solutions Crystallography chemistry.chemical_compound Biopolymers Crystallin Lens Crystalline Thiol Animals Cattle Electrophoresis Polyacrylamide Gel Oxidation-Reduction Research Article |
| Zdroj: | Proceedings of the National Academy of Sciences. 92:1067-1071 |
| ISSN: | 1091-6490 0027-8424 |
| DOI: | 10.1073/pnas.92.4.1067 |
| Popis: | Aqueous solutions of the bovine eye lens protein gamma II (or gamma B)-crystallin at neutral pH show a gradual increase in phase separation temperature, Tph, when allowed to stand for several weeks at room temperature without reducing agents. In a typical experiment, the Tph of the protein solution (218 mg/ml) increases from 2.5 +/- 1 degree C to 32.5 +/- 1 degree C after 21 days, and a new protein species, gamma IIH, is formed. The Tph of pure gamma IIH is at least 40 degrees C higher than that of pure gamma II. The average apparent hydrodynamic radius is 36 A for gamma IIH compared to 26 A for gamma II. The molecular mass of gamma IIH is approximately 41.5 kDa compared to 20 kDa for native gamma II. Therefore, gamma IIH is probably a dimer of gamma II crystallin. gamma IIH has a lower thiol content than gamma II and is not formed in the presence of dithiothreitol. We conclude that gamma IIH is a thiol oxidation product of gamma II-crystallin and is a dimer containing an intermolecular disulfide crosslink. Thus, some oxidative modifications of protein thiol groups lead to an increase in net attractive interactions between proteins. As a result, Tph increases and protein aggregates are formed. These two microscopic changes produce the increased light scattering associated with lens opacification. |
| Databáze: | OpenAIRE |
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