Renugopalakrishnan V, Horowitz P M, Glimcher M J
J Biol Chem. 1985 Sep 25;260(21):11406-13.
Phosvitin, a highly phosphorylated glycoprotein, represents the major fraction of hen egg yolk phosphoproteins. Circular dichroism, Fourier transform infrared spectroscopy, and Fourier transform infrared photoacoustic and fluorescence spectroscopic methods were employed to determine the secondary structure of the protein in both the solid and solution phases. This was supplemented by a Chou-Fasman type of predictive algorithm for the first 25 residues at the N terminus of the dephosphorylated protein. A three-compartment model consisting of alpha-helical, beta-sheet, and beta-turn components with beta-turns occurring at the interface between alpha-helical and beta-sheet regions in the proximity of O-phosphoserine residues is suggested from the combined analyses. Beta-sheets appear to be the dominant secondary structural component in phosvitin in the solid and solution phases. The suggested model bears many similarities to other phosphoproteins reported in the literature. The secondary structure of phosvitin is observed to be sensitive to environmental factors as previously reported although the present studies differ in some respects from earlier results. Preliminary results suggest that Ca2+ ions trigger a decrease in beta-sheet structure at pH 2.
卵黄高磷蛋白是一种高度磷酸化的糖蛋白，是鸡蛋蛋黄磷蛋白的主要成分。采用圆二色光谱、傅里叶变换红外光谱、傅里叶变换红外光声光谱和荧光光谱方法来测定该蛋白在固相和溶液相中的二级结构。通过Chou-Fasman型预测算法对去磷酸化蛋白N端的前25个残基进行补充分析。综合分析表明，存在一种由α-螺旋、β-折叠和β-转角组成的三室模型，β-转角出现在靠近O-磷酸丝氨酸残基的α-螺旋和β-折叠区域之间的界面处。β-折叠似乎是卵黄高磷蛋白在固相和溶液相中的主要二级结构成分。所提出的模型与文献中报道的其他磷蛋白有许多相似之处。正如之前报道的那样，尽管目前的研究在某些方面与早期结果不同，但观察到卵黄高磷蛋白的二级结构对环境因素敏感。初步结果表明，在pH 2时，Ca2+离子会引发β-折叠结构的减少。
