Cs. Bagyinka

PIXE analysis of proteins separated by polyacrylamide gel electrophoresis

Abstract The combination of PIXE and polyacrylamide gel electrophoresis (PAGE) is described. The gel sections were directly bombarded by 3 MeV protons and the Fe content of an iron-sulphur protein (HiPIP) separated by PAGE was measured.

Changes in the raman spectrum of frog sciatic nerve during action potential propagation

Abstract Raman spectra of frog sciatic nerves were recorded in different states of functioning. During excitation reversible changes were observed in the C40-carotenoid peaks enhanced by the resonance Raman effect. This change can be explained by transient carbon-carbon bond equalization of the polyene chain. Possible biological consequences are also discussed.

Metal composition analysis of hydrogenase from Thiocapsaroseopersicina by proton induced X-ray emission spectroscopy

Polyacrylamide gel electrophoresis combined with proton induced X-ray emission spectroscopy is suitable to identify and to determine the relative amounts of protein bound metals in situ. An analysis of the hydrogenase from Thiocapsa roseopersicina has shown the feasibility of the technique and provides new insight into the relative amount as well as the intramolecular location of Fe and Ni metal atoms in this enzyme.

Recent advances in biohydrogen research

Abstract. A fundamental and principal difficulty of the future energy supply is that the formation of fossil fuels is much slower than the rate of their exploitation. Therefore the reserves which can be recovered in an energetically feasible manner are shrinking parallel with an increasing world-wide energy demand. Among the alternative energy carriers, hydrogen is preferred because it is easy to transport and store and it burns to environmentally friendly water vapour when utilized. Hydrogen can be produced in biological systems, however, our understanding of the molecular details is just emerging.

Immune complex binding induces lateral lipid re-ordering in rat macrophage plasma membrane.

Abstract The plasma membrane of rat peritoneal exudate cells was spin labelled with fatty acid spin probes and structural changes induced by ligand binding to Fc and C3b receptors were followed. Neither antigens, nor monovalent immune complexes were capable of inducing any change. Multivalent ligands, both in soluble and particulate form, and to a lesser extent uncomplexed immunoglobulins were very effective in inducing membrane re-ordering, i.e. a decrease in fluidity. The phase transition region markedly broadened upon binding of multivalent immune complexes, indicating phase separation. There was a time lag of 5–10 min before the onset of lipid re-ordering was observed. We suggest that multivalent binding that is capable of cross-linking surface receptors initiates lateral phase separation and lipid re-ordering due to receptor aggregation.

Changes in the lateral ordering of the macrophage plasma membrane during Fc receptor mediated phagocytosis.

The macrophage plasma membrane was labelled with an intercalated 5-doxyl stearic acid spin probe, and structural changes induced by IgG-coated erythrocytes (EA) were followed with particular emphasis on the possible role of lipid reordering in the sequential events of phagocytosis. We present three lines of experimental evidence to show that these structural changes were induced by the lateral aggregation of cell surface Fc receptors. Cytochalasin B, an inhibitor of microfilament function, blocked this membrane reordering; if it was added after EA binding induced membrane reordering had already been detected for 15 min, a rapid reversal process was observed resulting in a reversible restoration of the initial order parameter value. We suggest that these structural changes indicate lipid-lipid lateral phase separation, in line with morphological findings.

Effect of binding of C3 and its fragments on the plasma membrane fluidity of lymphocytes

Abstract In our previous papers the complement-dependent inhibition of Fc receptors (FcRs) on human peripheral blood mononuclear cells (PMBCs) was described. The inhibition of FcRs was shown to be induced by C3b fragments fixed to the acceptor sites on the cells. To explain the mechanism of this phenomenon different models have been proposed. In the present investigations the effect of C3b, nascent C3b and aggregated C3 on the membrane fluidity of PMBCs was studied using intercalated spin probes. C3b molecules did not affect membrane fluidity when bound to C3b acceptor sites or to C3b receptors. On the other hand, binding of aggregated C3 decreases the membrane fluidity without inhibiting EA rosette formation. It can be concluded that fixing of nascent C3b fragments does not inhibit FcRs via fluidity modulation.

Mössbauer and EPR studies on iron-dihydroxybenzoic acid and iron-itoic acid chelate complexes

Low molecular weight iron-dihydroxybenzoic acid and iron—itoic acid complexes were investigated by Mössbauer and EPR spectroscopy. In strong acidic medium the iron is chelated in high spin ferrous form. By varying the pH of the medium a (S=2) Fe2+→(S=5/2) Fe3+ transition was found with a midpoint pH value of 4. From theg′-tensor anisotropy it is concluded that the metal atom is coordinated by six oxygen atoms in rhombically distorted octahedral configuration. The biological significance of these structural data is briefly discussed.