Interactions of human serum albumin with chlorogenic acid and ferulic acid.
The interactions of chlorogenic acid and ferulic acid with human serum albumin (HSA) have been investigated by fluorescence and Fourier transformed infrared (FT-IR) spectrometry. Fluorescence results showed that one molecule of protein combined with one molecule of drugs at the molar ratio of drug to HSA ranging from 1 to 10, and their binding affinities (KA) are 4.37 x 10(4) M(-1) and 2.23 x 10(4) M(-1) for chlorogenic acid and ferulic acid, respectively. The primary binding site for chlorogenic acid is most likely located on IIA and that for ferulic acid in IIIA. The main mechanism of protein fluorescence quenching was static quenching process. Combining the curve-fitting results of infrared amide I and amide III bands, the alterations of protein secondary structure after drug complexation were estimated. With increasing the drug concentration, the protein alpha-helix structure decreased gradually and the reduction of protein alpha-helix structure reached about 7% and 5% for protein binding with chlorogenic acid and ferulic acid individually at the drug to protein molar ratio of 30. This indicated a partial unfolding of HSA in the presence of the two acids. From the fluorescence and FT-IR results, the binding mode was discussed.
Kang
Juan
J
Analytical and Testing Center of Beijing Normal University, Beijing 100875, People's Republic of China.
Liu
Yuan
Y
Xie
Meng-Xia
MX
Li
Song
S
Jiang
Min
M
Wang
Ying-Dian
YD
D001665:Binding Sites; D002726:Chlorogenic Acid / Q000737:chemistry*; D003373:Coumaric Acids / Q000737:chemistry*; D006801:Humans; D015394:Molecular Structure; D011485:Protein Binding; D011487:Protein Conformation; D012709:Serum Albumin / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared
D003373:Coumaric Acids; D012709:Serum Albumin; D002726:Chlorogenic Acid; C004999:ferulic acid