38] Mössbauer spectroscopy in study of cytochrome cd1 from Thiobacillus denitrificans, desulfoviridin, and iron hydrogenase

Abstract

Publisher Summary This chapter discusses Mossbauer spectra, with emphasis on information contained in the spectra. It reviews the theoretical background necessary for understanding Mossbauer spectra of biological samples. Hyperfine interactions and their effect on Mossbauer spectra are also discussed. The chapter describes nuclear and electronic spin Hamiltonian commonly used for data analysis. Mossbauer spectroscopy is a nuclear resonance technique involving recoilless emission and absorption of γ photons in low-energy nuclear transitions. Because of the high-resolution nature of the technique, Mossbauer measurements can provide electronic and physical information concerning the iron centers in proteins in details that no other spectroscopy can match. For biological applications, the Mossbauer transition involves the ground and first excited states of the 57 Fe nucleus. To obtain an energy absorption spectrum representing the hyperfine interactions, the energy of the source radiation is brought into resonance with the transition energy of the absorber by moving the source relative to the absorber. The energy unit of Mossbauer spectra is therefore generally expressed in terms of source velocity.