Biomedical subjects

T Maly

Publications and source records attributed to T Maly.

3 recordsLinked to original sources

PubMed2006

Cluster N1 of complex I from Yarrowia lipolytica studied by pulsed EPR spectroscopy.

After reduction with nicotinamide adenine dinucleotide (NADH), NADH:ubiquinone oxidoreductase (complex I) of the strictly aerobic yeast Yarrowia lipolytica shows clear signals from five different paramagnetic iron-sulfur (FeS) clusters (N1-N5) which can be detected using electron paramagnetic resonance (EPR) spectroscopy. The ligand environment and the assignment of several FeS clusters to specific binding motifs found in several subunits of the complex are still under debate. In order to characterize the hyperfine interaction of the surrounding nuclei with FeS cluster N1, one- and two-dimensional electron spin echo envelope modulation experiments were performed at a temperature of 30 K. At this temperature only cluster N1 contributes to the overall signal in a pulsed EPR experiment. The hyperfine and quadrupole tensors of a nitrogen nucleus and the isotropic and dipolar hyperfine couplings of two sets of protons could be determined by numerical simulation of the one- and two-dimensional spectra. The values obtained are in perfect agreement with a ferredoxin-like binding structure by four cysteine amino acid residues and allow the assignment of the nitrogen couplings to a backbone nitrogen nucleus and the proton couplings to the beta-protons of the bound cysteine residues.

Electron Spin Resonance Spectroscopy↗

PubMed2002

Reconstruction after total gastrectomy.

After total gastrectomy it is necessary to realize the reconstruction of the upper part digestive tract. It is necessary to choose the reconstruction method, which provides good life quality, and extensive physiologic regulation of gastrointestinal hormones after total gastrectomy. There is no ideal reconstruction method. Nowadays there are about 70 kinds of reconstruction methods. It is very important to preserve the duodenal passage. Also the production of reservoir is important. The conclusions of studies are not homogeneous. The patients can benefit from the reconstruction preserving duodenal passage and formed by pouch. (Fig. 1, Ref. 23.).

Animals↗

PubMed2001

Chlorophyll and carotenoid radicals in photosystem II studied by pulsed ENDOR.

The stable carotenoid cation radical (Car(*+)) and chlorophyll cation radical (Chl(Z)(*+)) in photosystem II (PS II) have been studied by pulsed electron nuclear double resonance (ENDOR) spectroscopy. The spectra were essentially the same for oxygen-evolving PS II and Mn-depleted PS II. The radicals were generated by illumination given at low temperatures, and the ENDOR spectra were attributed to Car(*)(+) and Chl(Z)(*+) on the basis of their characteristic behavior with temperature as demonstrated earlier [Hanley et al. (1999) Biochemistry 38, 8189-8195]: i.e., (a) the Car(*)(+) alone was generated by illumination at < or =20 K, while Chl(Z)(*+) alone was generated at 200 K, and (b) warming of the sample containing the Car(*+) to 200 K resulted in the loss of the signal attributable to Car(*+) and its replacement by a spectrum attributable to the Chl(Z)(*+). A map of the hyperfine structure of Car(*+) in PS II and in organic solvent was obtained. The largest observed hyperfine splitting for Car(*+) in either environment was in the order of 8-9 MHz. Thus, the spin density on the cation is proposed to be delocalized over the carotenoid molecule. The pulsed ENDOR spectrum of Chl(Z)(*)(+) was compared to that obtained from a Chl a cation in frozen organic solvent. The hyperfine coupling constants attributed to the beta-protons at position 17 and 18 are well resolved from Chl(Z)(*+) in PS II (10. 8 and 14.9 MHz) but not in Chl a(*+) in organic solvent (12.5 MHz). This suggests a more defined conformation of ring IV with respect to the rest of the tetrapyrrole ring plane of Chl(Z)(*+) than Chl a(*+) probably induced by the protein matrix.

Carotenoids↗