Z. Szökefalvi-Nagy

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.

Location and quantification of metal ions in enzymes combining polyacrylamide gel electrophoresis and particle-induced X-ray emission.

A method is presented to identify and determine the relative amounts of protein-bound metal ionsin situ. Proteins or their subunits are directly scanned by a collimated proton beam of 3 MeV energy, and the characteristic X-rays produced are detected. The determination of Fe content of an iron-sulfur protein (HiPiP), as well as the Fe and Ni analysis of the hydrogenese fromThiocapsa roseopersina, have shown the feasibility of this technique.

K X-ray production cross-sections induced by 1.6–4.0 MeV deuterons

Abstract Thin P, S, Cl, K, Ni, Cu and Ga targets were bombarded by deuterons of 1.6–4.0 MeV energy. From the measured K X-ray intensities the X-ray production cross-sections were determined. The results are compared with proton induced cross-sections.

Elemental analysis of samples of biological origin relative to their protein content by means of charged particle bombardment.

The particle-induced X-ray emission (PIXE) method and the 14N(d,p)15N nuclear reaction are combined for simultaneous trace element and nitrogen determination. Measurement of nitrogen content often allows the relating of the elemental concentrations determined by PIXE to the protein content of the sample. For the measurements only a small amount of sample material is needed; therefore, it is possible to keep track of the quantity of a certain element in the successive steps of a biomedical separation process. In about 10 min, trace element concentrations in the ppm range can be determined with a statistical accuracy of about 10%.

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.

PIXE induced XRF analysis of trace amounts of iron in pure copper matrix

Abstract The iron atoms in a pure copper matrix are selectively excited by the characteristic X-ray radiation of Cu and Zn primary targets bombarded by 2.8 MeV protons. The sensitivities obtained in different experimental conditions are compared to each other and the combination of the Cu primary target with a 5 μm Co absorber in front of the Si(Li) detector was found to be the best choice.

Simultaneous PIXE and PIGE analysis of metalloproteins separated by cellulose acetate electrophoresis

The Fe and N distributions of myoglobin bands prepared by cellulose acetate electrophoresis were simultaneously measured by detecting the proton induced Fe K X-rays and the γ-rays of 2313 keV energy coming from the 14N(p, p′ γ)14N nuclear reaction at about 4 MeV proton energy. In the case of unstained bands the Fe and N distributions were very similar in shape and the integrated γ- and X-ray yields were found to be proportional to the amounts of myoglobin supplied for electrophoresis. In the cases of stained samples no quantitative conclusions could be drawn as a consequence of the drastic denaturation of the proteins caused by the staining.

L-shell X-ray production in W and Pb by protons of 1 to 3 MeV energy

Abstract L shell X-ray production cross sections were measured in W and Pb targets for incident proton energies of 1–3 MeV. Using the computer code AXIL ten L X-ray peaks were separated in both cases. The individual production cross section values obtained are presented in tables. Values of the I(Lβ)/I(Lα) and I(Lγ)/I(Lα) intensity ratios needed for quantitative concentration evaluations in trace element analysis are also given as a function of the incident proton energy. The experimental data are compared to theoretical ones obtained by ECPSSR calculations.

On the enhanced PIXE yields from thick iron fluoride targets

Abstract The enhancement effect observed by Peisach and his co-workers [Nucl. Instr. and Meth. B 75 (1993) 14] in thick target PIXE measurements on transition metal fluorides was demonstrated to occur on targets containing no fluorine at all. On the basis of the very characteristic background shape the enhancement was attributed to the charging up of the insulating target. Using a hot carbon filament both the charging and the enhancement were possible to eliminate. The time course of the whole phenomenon was also monitored.

Location of protein bands in cellulose acetate electrophoretograms measuring nitrogen distributions by the 14N(p,p′γ)14N nuclear reaction

Abstract The applicability of the resonance in the 14 N(p,p′γ) 14 N reaction at about 4 MeV proton energy was demonstrated to detect the nitrogen content of proteins separated by nitrogen free cellulose acetate electrophoresis. Making use of a collimated proton beam of 4 MeV energy, N distributions were successfully detected along the protein bands by help of γ-ray spectroscopy. The possible uncertainties and present difficulties in the measurements as well as further perspectives are also discussed.