Application of Mössbauer Spectroscopy in Study of Selected Biochemical Processes

The $\text{}^{57}$Fe, $\text{}^{119}$Sn, $\text{}^{129}$I, and $\text{}^{151}$Eu Mössbauer spectroscopy, scanning force microscopy, and optical fluorescence method were applied to study biological systems starting from porphyrins, through cytochromes and cell membranes until such a complex system as photosystem II. In Fe-porphyrin aggregates iron atoms are able to trap an electron exhibiting the mixed valence Fe$\text{}^{3+}$-Fe$\text{}^{2+}$ relaxation process. In ironcytochrome c the presence of two different Fe$\text{}^{3+}$ states are indicated, while in tincytochrome Sn appears in Sn$\text{}^{4+}$ and Sn$\text{}^{2+}$ states. From the temperature dependence of the mean square displacement of the resonance nuclei and from the diffusional broadening of the Mössbauer line it was possible to separate the vibrational, fast collective and slow collective motions in tinporphyrin and in iron- and tin-cytochrome c. The electronic state of iodine in oleic acid, the main constituent of cellular membranes, was determined. The molecular mechanism of triphenyltin interaction with membrane of red blood cells has been suggested and the model of haemolysis has been proposed. In photosystem II, Eu ions replacing calcium showed Eu$\text{}^{3+}$ to Eu$\text{}^{2+}$ transition after illumination with light, which points out the possible role of Ca$\text{}^{2+}$ ions in electron transfer in the process of photosynthetic water splitting process.