Molecular Size Dependency of Water Macromolecule Exchange Induced Frequency Shift

Introduction: A recent study suggested that water macromolecule exchange (WME) processes can contribute to the in vivo gray matter (GM) and white matter (WM) contrast in high field phase imaging [1]. Due to the complex nature of macromolecule-water interaction, bovine serum albumin (BSA) was used as a model system to demonstrate this effect. It is assumed that the WME interaction depends on the macromolecule size, conformation, and the surrounding chemical environment. The goal of this work was to study systematically the WME shift abilities of several proteins with different molecular weight (Mw) under neutral pH and to evaluate the possible relationship between WME shifts of different macromolecules and their potential contributions to in vivo phase contrast.