Structure and Conformation of Rhizoferrin and its Fe3+ Complexes

Abstract

Rhizoferrin is a simple but efficient siderophore and is potentially important for medical applications. The aim of this investigation is to determine the molecular structure of free rhizoferrin as well as its Fe3+ complexes, and to understand the mechanisms of cation (Fe3+)-binding specificity of rhizoferrin, using first-principle methods. The optimized molecular structures, and the calculated Nuclear Magnetic Resonance properties, such as chemical shifts for 13C and 1H and indirect dipole dipolecouplings for 1H, will be presented and compared with the experimental data. The nuclear quadrupole interaction parameters will be discussed as an attempt to understand the charge distribution and electric field gradient. Possible influence of deprotonation of citrate carboxylate groups on Fe3+-rhizoferrin complex formation will be discussed. This is, to the best of our knowledge, the first theoretical study of rhizoferrin and its metal complexes, and it provides a critical insight and guidance to the structural basis of metal chelation by rhizoferrin.