EVIDENCE FOR THE INTERACTION BETWEEN (-)-EPIGALLOCATECHIN GALLATE ANDHUMAN PLASMA-PROTEINS FIBRONECTIN, FIBRINOGEN, AND HISTIDINE-RICH GLYCOPROTEIN

Human plasma proteins were subjected to affinity chromatography with ( -)-epigallocatechin gallate (EGCg)-agarose, and the bound proteins wer e examined by sodium dodecylsulfate-polyacrylamide gel electrophoresis . A molecular weight evaluation of the protein bands suggested the pre sence of three proteins, fibronectin, fibrinogen, and a 75-kDa protein . When human serum was used, the 75-kDa protein dominated the bound fr action. The determination of the partial amino acid sequence of a pept ide derived by endopeptidase digestion of this fraction suggested the 75-kDa protein to be histidine-rich glycoprotein (HRG). The presence o f these proteins in the bound fraction was confirmed by the immunoblot ting method. Affinity chromatography of the individual proteins indica ted that fibrinogen and HRG had direct affinity for EGCg. Dot binding assays demonstrated the interaction of EGCg with these proteins. The m ethod also showed that only gallate-containing catechins were bound by these proteins. These data suggest that when EGCg is absorbed in the body through the digestive system, it may interact with these proteins in blood plasma.