High stability of apo-cytochrome c′ from thermophilic Hydrogenophilus thermoluteolus

Abstract

Apo-cytochomes c without heme are usually unstructured. Here we showed that apo-form of thermophilic Hydrogenophilus thermoluteolus cytochrome c′ (PHCP) was a monomeric protein with high helix content. Apo-PHCP was thermally stable, possibly due to the hydrophobic residues and ion pairs. PHCP is the first example of a structured apo-cytochrome c′, which will expand our view of hemoprotein structure formation.