基于pH变性及圆二色谱检测的PC645空间结构状态OA

By monitoring absorption spectra and circular dichroism(CD)spectra across different pH conditions,we investigated the stability of phycocyanin PC645's chromophore and spatial structure,along with its energy transfer function.The results demonstrated that:1)PC645 maintained stable absorption peaks,CD peaks,and secondary structure ratios with pH 3.5-10,with optimal protein conformation and functional state observed at pH 5-7.Nota-bly,pH 5 appeared to represent a critical transition point for physiological functional changes;2)Moderate struc-tural alterations occurred at extreme pH values(pH 3-3.5 and pH 10-11),where secondary structure changes were observed while tertiary and quaternary structures and energy absorption functions remained intact,suggesting the latter play a more crucial role in light harvesting.The 525 nm CD peak emerged as a reliable indicator of qua-ternary structural integrity;3)Significant structural disintegration occurred at pH<3 and pH>10,with acid denat-uration inducing secondary structure folding while alkaline conditions caused irregular peptide chain coiling.These findings highlight PC645's remarkable pH adaptability,suggesting its strong potential as a versatile fluorescent probe capable of withstanding diverse chemical environments for various fluorescence detection applications.