通过圆二色性研究溶液中γ-玉米醇溶蛋白的二级结构。

gamma-Zein secondary structure in solution by circular dichroism.

作者信息

Bicudo Tatiana C, Bicudo Rogério C, Forato Lucimara A, Beltramini Leila M, Batista Luiz A R, Filho Rubens Bernardes, Colnago Luiz A

机构信息

Universidade de São Paulo, Instituto de Química de São Carlos, Av. Trabalhador Sãocarlense, 400, São Carlos, SP 13560-970, Brazil.

出版信息

Biopolymers. 2008 Mar;89(3):175-8. doi: 10.1002/bip.20884.

DOI:10.1002/bip.20884

PMID:17994554

Abstract

The proline-rich N-terminal domain of gamma-zein has been reported in relevant processes, which include its ability to cross the cell membranes. Evidences indicate that synthetic hexapeptide (PPPVHL), naturally found in N-terminal portion of gamma-zein, can adopt the polyproline II (PPII) conformation in aqueous solution. The secondary structure of gamma-zein in maize protein bodies had been analyzed by solid state Fourier transform infrared and nuclear magnetic resonance spectroscopies. However, it was not possible to measure PPII content in physiological environment since the beta-sheet and PPII signals overlap in both solid state techniques. Here, the secondary structure of gamma-zein has been analyzed by circular dichroism in SDS aqueous solution with and without ditiothreitol (DTT), and in 60% of 2-propanol and water with DTT. The results show that gamma-zein has high helical content in all solutions. The PPII conformation was present at about 7% only in water/DTT solution.

摘要

γ-醇溶蛋白富含脯氨酸的N端结构域已在相关过程中被报道，其中包括其穿越细胞膜的能力。有证据表明，天然存在于γ-醇溶蛋白N端部分的合成六肽（PPPVHL）在水溶液中可采用多聚脯氨酸II（PPII）构象。玉米蛋白体中γ-醇溶蛋白的二级结构已通过固态傅里叶变换红外光谱和核磁共振光谱进行了分析。然而，由于在这两种固态技术中β-折叠和PPII信号重叠，因此无法在生理环境中测量PPII含量。在此，通过圆二色性在含有和不含有二硫苏糖醇（DTT）的SDS水溶液中以及在含有DTT的60%异丙醇和水的混合液中对γ-醇溶蛋白的二级结构进行了分析。结果表明，γ-醇溶蛋白在所有溶液中都具有较高的螺旋含量。PPII构象仅在水/DTT溶液中以约7%的比例存在。