Hornshaw M P, McDermott J R, Candy J M, Lakey J H
MRC Neurochemical Pathology Unit, Newcastle General Hospital, Newcastle upon Tyne, United Kingdom.
Biochem Biophys Res Commun. 1995 Sep 25;214(3):993-9. doi: 10.1006/bbrc.1995.2384.
Using CD spectroscopy we have investigated the effect of Cu2+ on the secondary structure of synthetic peptides Octa4 and Hexa4 corresponding to tetra-repeats of the octapeptide of mammalian PrP and the hexapeptide of chicken PrP. In addition, fluorescence spectroscopy was used to estimate the dissociation constants (Kd), of Cu2+ binding by both peptides. Both peptides exhibited unusual CD spectra, complicated by the high proportion of aromatic residues, revealing little secondary structure in aqueous solution. Addition of Cu2+ to Hexa4 induced an increase in random coil to resemble Octa4. The fluorescence of both peptides was quenched by Cu2+ and this was used to calculate Kd's of 6.7 microM for Octa4 and 4.5 microM for Hexa4. Other divalent cations showed lesser effects on the fluorescence of the peptides.
我们利用圆二色光谱研究了Cu2+对合成肽Octa4和Hexa4二级结构的影响，这两种肽分别对应哺乳动物朊蛋白八肽和鸡朊蛋白六肽的四重复序列。此外，还利用荧光光谱估算了两种肽与Cu2+结合的解离常数（Kd）。两种肽均呈现出异常的圆二色光谱，由于芳香族残基比例较高而变得复杂，表明在水溶液中二级结构较少。向Hexa4中添加Cu2+会导致无规卷曲增加，类似于Octa4。两种肽的荧光都被Cu2+淬灭，据此计算出Octa4的Kd为6.7微摩尔，Hexa4的Kd为4.5微摩尔。其他二价阳离子对肽的荧光影响较小。
