Is the heme pocket region modulated by disulfide-bridge formation in fish and amphibian neuroglobins as in humans?

► The neuroglobins (Ngb) of Xenopus, Danio and icefish, were studied using EPR. ► The effect of the different Cys residues present was studied. ► Reduction of the disulfide bond does not change heme pocket structure in fish Ngb. ► Mutation of Cys residues in Xenopus resulted in an altered heme structure. ► The amphibian Ngb is more resistant to H2O2-induced denaturation than other Ngbs.