Iron Biomineral Growth from the Initial Nucleation Seed in L‐Ferritin
Silvia Ciambellotti, Cecilia Pozzi, Stefano Mangani, Paola Turano
Abstract
Abstract X‐ray structures of homopolymeric human L ‐ferritin and horse spleen ferritin were solved by freezing protein crystals at different time intervals after exposure to a ferric salt and revealed the growth of an octa‐nuclear iron cluster on the inner surface of the protein cage with a key role played by some glutamate residues. An atomic resolution view of how the cluster formation develops starting from a (μ 3 ‐oxo)tris[(μ 2 ‐glutamato‐κO:κO’)](glutamato‐κO)(diaquo)triiron(III) seed is provided. The results support the idea that iron biomineralization in ferritin is a process initiating at the level of the protein surface, capable of contributing coordination bonds and electrostatic guidance.