Regini Justyn W, Grossmann J Günter, Timmins Peter, Harding John J, Quantock Andrew J, Hodson Stuart A, Elliott Gerald F
School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, United Kingdom.
Invest Ophthalmol Vis Sci. 2007 Jun;48(6):2695-700. doi: 10.1167/iovs.06-0559.
Alpha-crystallin, a ubiquitous molecular chaperone, is found in high concentrations in the lens. Its structure and precise mechanism of action, however, are unknown. The purpose of these experiments was to further the understanding of the chaperone function of alpha-crystallin.
X-ray- and neutron-solution-scattering studies were used to measure the radius of gyration of bovine lens alpha-crystallin when complexed with its target protein beta-crystallin in both normal and heavy-water-based solutions. Spectrophotometry was used as a chaperone assay.
The radius of gyration of alpha-crystallin on its own and when mixed with beta-crystallin was 69 +/- 1 A at 35 degrees C and increased with the temperature. In contrast to H2O-buffered solutions, the radius of gyration did not increase significantly in D2O-buffered solutions up to 55 degrees C, and at 70 degrees C was, on average, some 15 to 20 A smaller.
Bovine lens alpha-crystallin in solution can be modeled as a fenestrated spherical shell of diameter 169 A. At physiological temperatures, a weak interaction between alpha- and beta-crystallin occurs, and beta-crystallin is located in the fenestrations. Deuterium substitution indicates that the superaggregation process is controlled by hydrogen bonding. However, the chaperone process and superaggregation appear not to be linked.
α-晶状体蛋白是一种普遍存在的分子伴侣，在晶状体中含量很高。然而，其结构和确切作用机制尚不清楚。这些实验的目的是进一步了解α-晶状体蛋白的伴侣功能。
利用X射线和中子溶液散射研究，在正常溶液和重水溶液中测量牛晶状体α-晶状体蛋白与其靶蛋白β-晶状体蛋白复合时的回转半径。使用分光光度法作为伴侣测定法。
α-晶状体蛋白单独存在时以及与β-晶状体蛋白混合时，在35℃下的回转半径为69±1 Å，并随温度升高而增加。与水缓冲溶液相比，在重水缓冲溶液中，回转半径在55℃之前没有显著增加，在70℃时平均小约15至20 Å。
溶液中的牛晶状体α-晶状体蛋白可模拟为直径169 Å的有孔球壳。在生理温度下α-晶状体蛋白和β-晶状体蛋白之间发生弱相互作用，β-晶状体蛋白位于孔中。氘取代表明超聚集过程受氢键控制。然而，伴侣过程和超聚集似乎没有联系。
