Interaction of polyphenols with proteins: binding of (-)-epigallocatechin gallate to serum albumin, estimated by induced circular dichroism.
The binding of (-)-epigallocatechin gallate (EGCG), a representative natural polyphenol, to human serum albumin (HSA) and bovine serum albumin (BSA) was investigated using induced circular dichroism (CD). The site of the binding EGCG-HSA was analyzed based on the competition with drugs with known binding sites on HSA, such as phenylbutazone (PB) and diazepam (DP). Double-reciprocal plot analyses showed the competitive relations with the site-I- (PB and tolbutamide, TB) and site-II-binding drugs (DP and ibuprofen, IP) indicating the binding of EGCG to sites I and II on HSA, while digitoxin (DG), a site-III-binding drug, did not affect the binding of EGCG. In an analogous way, the competitive relations were observed between EGCG and the site-I- (PB and TB) and site-II-binding (ethacrynic acid, EA) drugs for the binding of EGCG and BSA. The site-III drug DG also showed competitive binding with EGCG to BSA. The binding of EGCG to the albumins indicated its affinity to sites I and II on HSA, while competitive binding for all three sites was observed on BSA.
Nozaki
Akiko
A
Department of Pharmacognosy, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Tsushima, Japan.
Hori
Mami
M
Kimura
Toshikiro
T
Ito
Hideyuki
H
Hatano
Tsutomu
T
D000818:Animals; D001665:Binding Sites; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry; D002417:Cattle; D002942:Circular Dichroism; D005419:Flavonoids / Q000737:chemistry*; D006801:Humans; D007202:Indicators and Reagents; D010636:Phenols / Q000737:chemistry*; D059808:Polyphenols; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry*; D012709:Serum Albumin / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry
D005419:Flavonoids; D007202:Indicators and Reagents; D010636:Phenols; D059808:Polyphenols; D011506:Proteins; D012709:Serum Albumin; D012710:Serum Albumin, Bovine; D002392:Catechin; C045651:epigallocatechin gallate