Messmer M, Chakrabarti B
Department of Ophthalmology, Harvard Medical School, Boston, MA 02114.
Exp Eye Res. 1988 Aug;47(2):173-83. doi: 10.1016/0014-4835(88)90001-2.
To gain insight into the molecular features of the high-molecular-weight (HMW) fraction of soluble lens proteins and their changes in aging, we isolated this fraction from the nucleus of calf and cow lenses and measured fluorescence and circular dichroism (CD) properties of the samples. Not only was there an increase in the HMW fraction in the older lens, but there was also an age-related difference in tertiary structure that was clearly manifested in the fluorescence and CD parameters. The far-u.v. CD of low- and high-molecular-weight proteins do not differ significantly in band position and magnitude, but the near-u.v. CD of HMW protein does differ distinctly from that of all other crystallins (alpha, beta and gamma); the entire CD spectrum of this protein is displayed in the negative region. Millipore filtration further revealed that HMW aggregates are essentially a polydisperse population of different conformation (tertiary structure) and that these aggregates are associated by non-convalent interactions. This association is caused mainly by the apolar (hydrophobic) nature of the constituent protein. alpha-Crystallin has more hydrophobic domain along the peptide chain that do other crystallins and thus is likely to be the predominant protein in HMW aggregates.
为深入了解可溶性晶状体蛋白高分子量（HMW）部分的分子特征及其在衰老过程中的变化，我们从小牛和母牛晶状体的核中分离出该部分，并测量了样品的荧光和圆二色性（CD）特性。不仅老年晶状体中HMW部分增加，而且三级结构存在与年龄相关的差异，这在荧光和CD参数中明显体现。低分子量和高分子量蛋白质的远紫外CD在谱带位置和强度上没有显著差异，但HMW蛋白质的近紫外CD与所有其他晶状体蛋白（α、β和γ）明显不同；该蛋白质的整个CD光谱显示在负区域。微孔过滤进一步表明，HMW聚集体本质上是具有不同构象（三级结构）的多分散群体，并且这些聚集体通过非共价相互作用结合。这种结合主要是由组成蛋白质的非极性（疏水）性质引起的。α-晶状体蛋白沿肽链比其他晶状体蛋白具有更多的疏水结构域，因此可能是HMW聚集体中的主要蛋白质。
