Investigation of the interaction between vitamin C and vitamin B12 with human serum albumin using spectroscopic techniques

Alsamamra, Husain
Hawwarin, Ibrahim
Abusharkh, Sawsan
Abutier, Musa
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Vitamin C is an important regulatory for iron uptake and vitamin B12 is essential for proper functioning of folic acid. Human serum albumin is an abundant plasma protein, the major soluble protein constituent of the circulatory system and has many physiological functions including transport of a variety of compounds. In this work, the molecular interaction between vitamin C and B12with human serum albumin was investigated using constant protein concentration and various drug concentrations at pH 7.4. Three different spectroscopic methods were used; fluorescence spectroscopy, UV absorption and FT-IR spectroscopy. From spectral analysis, both vitamins showed a strong ability to quench the intrinsic fluorescence of human serum albumin through a static quenching procedure.The binding constant (k) is estimated from UV-absorption as k=1.28×104 M-1 for HSA-Vitamin C and k=2.21×104 M-1 for HSA-vitamin B12. Both results showed a good agreement with the binding constants obtained from the modified Stern-Volmer equation using florescence technique. The appearance or disappearance of the bands is a good sign to understand the mechanisms at the molecular level. The FT-IR spectral changes indicates an increase of intensity for HSA-vitamin C interaction and a reduction of intensity for HSA-vitamin B12 interaction. For HSA-vitamin C complexes, positive features are related to increase in intensity of the amide I and II bands upon drugcomplexation due to drug binding to protein difference spectra of vitamin B12-HSA complexes, intensity decreases as the concentration of vitamin B12 increases for amide I band at 1656cm-1 , and amid II band at 1544 cm-1 , this results in stabilization by hydrogen bonding by having the C-N bond assuming partial double character due to a flow of electrons from the C=O to the C-N. C=O, C-N and N-H groups. While in the
Vitamin C,, Vitamin B12, Human serum albumin, UV-spectroscopy, Fluorescence spectroscopy, FT-IR