Characterization of copper binding to Riboflavin Binding Protein

Abstract

Riboflavin Binding Protein (RBP), abundant in both the yolk and white portions of avian egg, has been shown to bind copper in a 1:1 molar ratio under dialysis conditions. Binding forms a well‐defined Type II site with g values that indicate an oxygen rich environment for the copper. XAS studies indicate a mixture of copper(I) and copper(II) in the XANES spectrum; spin quantitation by cw‐EPR suggests that all of the copper(I) observed by XANES cannot be accounted for by photo‐oxidation during XAS, although no external reducing agents were added and dialysis was performed aerobically. We propose a possible role for RBP in copper transport and storage in avian embryo.