Reversible temperature-dependent high- to low-spin transition in the heme Fe–Cu binuclear center of cytochrome ba₃ oxidase

Abstract

A reversible temperature-dependent high- to low-spin transition with T1/2 = −60 °C has been observed in the resonance Raman spectra of the equilibrium reduced and photoreduced heme a3 of the thermophilic ba3 heme–copper oxidoreductase.

Discrete Ligand Binding and Electron Transfer Properties of ba3-Cytochrome c Oxidase from Thermus thermophilus: Evolutionary Adaption to Low Oxygen and High Temperature Environments

“…Combining the present and previous data, the most reliable scenario involves a cluster of groups, water molecules and amino acid residues as the proton-loading site of cytochrome ba 3 oxidase . Since this hydrophilic feature is structurally conserved among all the characterized C c Os, there is consensus that is the water/proton exit site. − …”

Reversible thermally induced spin crossover in the myoglobin–nitrito adduct directly monitored by resonance Raman spectroscopy

“…SCO phenomena are being studied in enzymes as they play vital roles in biochemical reactions, as well as in synthetic heme and non-heme systems due to their potential applications in nanotechnology, molecular electronics and spintronics. [26][27][28][29][30][31][32][33] Resonance Raman spectroscopy is a valuable tool for detection of SCO phenomena in heme proteins and we have previously utilized it to report an unusual ligand-concentration dependent spin transition in the green pigment of Mb, namely the ferric heme nitrito/2-nitrovinyl species. 23 The resonance Raman spectra of heme proteins comprise of multiple vibrational modes that are sensitive to oxidation, spin and coordination of the heme Fe center, while isotopic substitution of the ligand allows the observation of the binding mode to the heme Fe center.…”

“…SCO phenomena are being studied in enzymes as they play vital roles in biochemical reactions, as well as in synthetic heme and non-heme systems due to their potential applications in nanotechnology, molecular electronics and spintronics. 26–33…”