ABSTRACT
The aim of the study was establishment of mechanisms of bilirubin oxidation and their involvement in the physiological and pathological processes in the living body (EPR study of photoradiated bilirubin). The photosensitized formation of free radical of bilirubin with g=2.003 and DeltaH=1.0 mTl, under action of the blue light with lambda(max)=450 nm by means of electronic spin resonance (ESR) was shown. Irradiation of sample in vacuum by visible light does not cause formation of free radicals. Irradiation of powder of bilirubin and also of its solution in chloroform leads to formation of the radical of bilirubin. The analysis of a spectrum (ESR) as powder also its solution in chloroform, that induced free radical belongs to bilirubin but not of solution was shown. Irradiation of a solution of bilirubin in chloroform causes absorption spectrum with lambda(max)=650 nm, characterized for absorption of solutions biliverdin in chloroform.
Subject(s)
Antioxidants/metabolism , Bilirubin/metabolism , Gallstones/metabolism , Antioxidants/chemistry , Bilirubin/chemistry , Bilirubin/radiation effects , Chloroform/chemistry , Electron Spin Resonance Spectroscopy , Gallstones/chemistry , Humans , Oxidation-Reduction , Reactive Oxygen Species/metabolismABSTRACT
It has been shown by microcalorimetry that UV-irradiation cardinally alters the temperature dependence of heat capacity of a collagen solution and decreases the enthalpy of collagen heat denaturation. By using the method of electron spin resonance (ESR), it was found that the primary products of UV-irradiated acid-soluble collagen are the atomic hydrogen and the anion radical of acetic acid. The latter, under the influence of long-wavelength UV light, is transformed into the methyl radical, which interacts with acetic acid to produce acetic acid radical. The above free radicals interact with the collagen molecule, as a result of which seven superfine components with the split of deltaH = 1.13 mT are obtained in the ESR spectrum. It is assumed that this spectrum is related to the free radical that occurred in the proline residue of the collagen molecule. In this particular case, this is a major structural defect in the triple helix of collagen, which results in instability of the macromolecule.
Subject(s)
Collagen/chemistry , Collagen/radiation effects , Electron Spin Resonance Spectroscopy , Ultraviolet Rays , Animals , Calorimetry , Methane/analogs & derivatives , Methane/analysis , Rats , SolutionsABSTRACT
Complexes of Cu(II) ions with globular proteins (human serum albumin, bovine serum albumin, egg albumin, lisozim and DNA) have been studied using the ESR method. It was shown that Cu(II) ions may be use as structural "spin-label" to study conformational dynamics of macromolecules, including structural transition in biopolymers.
Subject(s)
Copper/chemistry , DNA/chemistry , Proteins/chemistry , Spin Labels , Electron Spin Resonance Spectroscopy , Nucleic Acid Conformation , Protein ConformationABSTRACT
ESR study was carried out of the interaction between Zn2+, Cu2+, Ca2+, Mg2+ ions and human serum albumin (HSA) in the presence of Mn2+ ions which depends on pH. Competitive binding of these ions with "manganese-binding" sites of albumin was shown to depend on pH. An analysis of concentration dependence of binding these ions with human serum albumin confirmed earlier supposition about the nature of the binding sites of Mn2+ ions with HSA.
