Binding of Vitamin K1(Phylloquinone) to Human Serum Albumin(HSA):Spectroscopic studies

Abu Teir, Musa M
Hourani, Ola
Darwish, Saker M
Abu-hadid, Mahmoud M
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The interaction of hydrophobic vitamin (vitamin K1) with human serum albumin (HSA) at physiological (pH 6.9- 7.4) has been studied using UV-VIS spectrometer, and an FT-IR spectroscopy. The interaction of hydrophobic vitamin (vitamin K1) with HSA has been investigated by using UV-absorption, and Fourier transforms infrared (FT-IR) spectroscopy. The binding constant of vitamin K1 has been determined by UV-absorption. The value of the binding constant for vitamin K1 -HSA is calculated at room temperature 293 K and it was determined as 60 M����. FT-IR spectroscopy with Fourier self- deconvolution technique and second derivative resolution enhancement procedures were applied in the analysis of the amide I, amid II, and amid III regions to determine the protein secondary structure and hydrophobic vitamin binding mechanisms. All peaks positions in the three amide regions (amid I, amide II and amide III) have been assigned and any changes due to concentration changes have been investigated. The FTIR spectra measurements indicate a change in the intensity of absorption bands due to change in the concentrations in drugs. In addition a larger intensity decrease in the absorption band of α-helix relative to that of β-sheets has been observed. This variation in intensity is related indirectly to the formation of H-bonding in the complex molecules, which accounts for the different intrinsic propensities of α-helix and β-sheets.
Vitamin K1, amide I-III, binding mode, binding constant, protein secondary structure, Fourier transform IR, UV–spectroscopy, Fluorescence spectroscopy