Effect of heat denaturation of intact cells and chromatophores of chromatium minutissimum on their Moessbauer spectra

The aim was to study the changes in Moessbauer spectra of chromatophores as well as of intact cells of Chromatium minutissimum in accordance with the degree of hydration and duration of denaturation. Sharp alterations in the gamma-resonance spectra of intact cells observed after heating for 30 min at 180 0C (the spectrum exhibited a doublet with delta = 1 mm/s and Δ = 2 mm/s), while the appearance of a doublet with delta = 1.5 mm/s and Δ = 3.1 mm/s was observed in a lyophilized chromatophore sample after heating for 90 min at 120 0C. The character of changes f' (the probability of the Moessbauer effect) in the spectra of moist and dried material is different. The reason for a f' decrease after heating of lyophilized samples is, probably, the destruction of the hydration layers of the biopolymers (''bound water'') responsible for its structural stability. (author)