Biochemical Characterization and Ligand Binding Properties of Neuroglobin, a Novel Member of the Globin Family

摘要: Neuroglobin is a recently discovered member of the globin superfamily that suggested to enhance O2 supply vertebrate brain. Spectral measurements with human and mouse recombinant neuroglobin provide evidence for hexacoordinated deoxy ferrous (Fe2+) form, indicating His-Fe2+-His binding scheme. or CO can displace endogenous protein ligand, which identified as distal histidine by mutagenesis. The ferric (Fe3+) form also ligand E7-His does not exhibit pH dependence. Flash photolysis studies show high recombination rate (kon) slow dissociation (koff) both CO, intrinsic affinity these ligands. However, because rate-limiting step in combination involves be slowin vivo. Because this competition, observed average (1 torr at 37 °C). has autoxidation rate, resulting an oxidation °C air within few minutes. oxidation/reduction potential (E′o = −129 mV) lies physiological range. Under natural conditions, occurs monomer disulfide-dependent formation dimers. biochemical kinetic characteristics are discussed view possible functions