Loading...
Please wait, while we are loading the content...
Small-angle X-ray Scattering Characterization of Lens Crystallin Proteins
| Content Provider | Semantic Scholar |
|---|---|
| Author | Mirarefi, Amir Y. Devries, Arthur L. Kiss, Andor J. Boutet, Sébastien Ramakishnan, Sadhu Balasundaram Cheng, C.-H. Robinson, Ian Zukoski, Charles F. |
| Copyright Year | 2004 |
| Abstract | Introduction Cataract formation refers to the opacification of the eye lens and is a serious medical condition. More than 50% of humans over the age of 65 develop cataracts, which can result in total blindness. The mechanisms for cataract formation are poorly understood [1]. Changes in the aggregation state of the proteins in the eye lens are responsible for cataract formation. One form of cataract formation occurs when the eye proteins reversibly aggregate upon cooling and the lens undergoes a reversible opacification [2]. This effect has been studied in depth in mammals. While mammalian eyes exhibit cold cataracts beginning at temperatures below 19°C, the lenses of the Antarctic fish, which lives at −2°C, are completely clear [3]. In this study, we characterize differences in eye lens proteins to understand the variations in protein aggregation. Fish lenses are dense in protein and thus generate a refractive index large enough to focus light [4]. The mechanism for focusing lies in changing the eye shape. In bovine lenses, however, protein densities are not as high, and focusing results from changes in the lens shape. The dense protein state of the fish lens results in large osmotic pressures, unless the proteins are attractive. The evolutionary drive to focus light in an aqueous environment has resulted in a balance of protein concentration and strength of attraction, where the osmotic pressure of the cell matches the external osmotic pressure, and lens transparency is achieved. The bovine lens has been treated as a system for modelling the physical and biochemical properties of crystallin proteins, which are categorized by size as: α, β, and γ proteins. These proteins interact in complex manners such that the α and β proteins exist as aggregates and the γ proteins are monomeric. The γ proteins have been implicated in cold cataract formation. Even though there is substantially more γ protein in the fish lens, there is no evidence of cold cataract formation. Two issues of particular interest in a comparative study are the protein interactions that result in γ protein aggregation and how this state of aggregation is influenced by temperature. Here we explore changes that occur in an intact fish lens microstructure as the temperature is varied, and we compare observations on the lenses of fish that live in different climates. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://www.aps.anl.gov/sites/www.aps.anl.gov/files/APS-sync/activity_reports/apsar2002/MIRAREF1.PDF |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
