Shi Yan-Bo, Fang Jiang-Lin, Liu Xiao-Yu, Du Liang, Tang Wen-Xia
State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, Nanjing University, Nanjing 210093, China.
Biopolymers. 2002 Oct 15;65(2):81-8. doi: 10.1002/bip.10195.
The secondary structures of porcine brain Cu(4)Zn(3)-metallothionein (MT)-III and Cd(5)Zn(2)MT-I, Cd(5)Zn(2)MT-II, and Zn(7)MT-I from rabbit livers in the solid state are investigated by Fourier transform IR spectroscopy (FTIR) and Fourier transform Raman spectroscopy (FT-Raman). The Cu(4)Zn(3)MT-III contains 26-28% beta-turns and half-turns, 13-14% 3(10)-helices, 47-49% random coils, and 11-12% beta-extended chains. The structural comparison of porcine brain Cu(4)Zn(3)MT-III with rabbit liver Cd(5)Zn(2)MT-I (II) and Zn(7)MT-I shows that the contents of the random coil structure are obviously increased. The results indicate that the insert of an acidic hexapeptide in the alpha domain of Cu(4)Zn(3)MT-III possibly forms an alpha helix. However, because the bands assigned to the alpha-helix and random coil structures are overlapped in the spectra, the content of random coil structures in Cu(4)Zn(3)MT-III is therefore higher than those in Cd(5)Zn(2)MT-I, Cd(5)Zn(2)MT-II, and Zn(7)MT-I.
采用傅里叶变换红外光谱（FTIR）和傅里叶变换拉曼光谱（FT - Raman）对固态的猪脑Cu(4)Zn(3)-金属硫蛋白（MT）-III以及来自兔肝脏的Cd(5)Zn(2)MT - I、Cd(5)Zn(2)MT - II和Zn(7)MT - I的二级结构进行了研究。Cu(4)Zn(3)MT - III含有26 - 28%的β - 转角和半转角、13 - 14%的3(10)-螺旋、47 - 49%的无规卷曲以及11 - 12%的β - 伸展链。猪脑Cu(4)Zn(3)MT - III与兔肝脏Cd(5)Zn(2)MT - I（II）和Zn(7)MT - I的结构比较表明，无规卷曲结构的含量明显增加。结果表明，Cu(4)Zn(3)MT - III的α结构域中插入的酸性六肽可能形成α螺旋。然而，由于光谱中归属于α - 螺旋和无规卷曲结构的谱带重叠，因此Cu(4)Zn(3)MT - III中无规卷曲结构的含量高于Cd(5)Zn(2)MT - I、Cd(5)Zn(2)MT - II和Zn(7)MT - I中的含量。
