Search PubMed⌕ Search

Biomedical subjects

B Nagy

Publications and source records attributed to B Nagy.

At least 163 records · Page 9Linked to original sources
PubMed1975

The substructure of heavy meromyosin. The effect of Ca2+ and Mg2+ on the tryptic fragmentation of heavy meromyosin.

Heavy meromyosin, obtained by tryptic digestion of myosin, containing two main polypeptides whose masses were estimated as 81,000 and 74,000 dlatons from Na dodecyl-SO4 polyacrylamide gel electrophoresis, was further digested with trypsin. The Ca2+-activated ATPase activity remainded unchanged and the K+-EDTA activity increased while various smaller fragments were formed. The formation of some of these fragments is affected by Ca2+ or Mg2+ as first shown by Bálint et al. (Bálint, M., Schaefer, A., Biro, N. A., Menczel, L., AND Fejes, E. (1971) J. Physiol. Chem. Phys. 3, 455). On the basis of the time course of the appearance of fragments the following relationship emerges: see article. The 64K leads to 60K step is inhibited by divalent cations, while the breakdown of the 74K fragment is accelerated. The effect of Ca2+ was maximal at 0 similar to 0.1 muM, that of Mg2+ at 10 muM. The original light chains of myosin are not present in the heavy meromyosin serving as the starting material, but peptide material appears on electrophoresis in positions starting material, but peptide material appears on electrophoresis in positions where the light chains would be found. The fragments marked by an asterisk are considered to ba alpha-helical on the basis of their solubility at low ionic strength after precipitation with ethanol (Bálint et al.). The fact that alpha helical fragments are derived from the 60,000-dalton fragment indicateds that it is adjacent to the light meromyosin in the intact myosin while the 74,000- dalton fragment would be part of heavy meromysoin subfragment 1. Chromatography of Sephadex G-200 separates fractions with ATPase activity corresponding to heavy meromyosin and heavy meromyosin subfragment 1. Electrophoresis of these Sephadex fractions suggests that the main peptide constituting heavy meromysoin subfragment 1 is connected by noncobalent forces to a portion of the rod that is not immediately adjacent to it in the primary sequence. The significance of this finding is discussed in terms of the flexibility of the myosin head.

Adenosine Triphosphatases↗
PubMed1975

Nature of alkanes in beef heart lipids.

n-Alkanes have been found to be the major saturated hydrocarbon components in the fatty tissues on beef heart. These alkanes consist of a homologous series C14-C35, with the C29 and C31 n-alkanes being most abundant. C16, C19, and C20 isoprenoid alkanes also were identified. A C17 isoprenoid alkane tentatively was identified. The fatty tissues on beef heart contained 32 mug/g saturated hydrocarbons. The distribution pattern of these saturated hydrocarbons is in marked contrast to the alkane distribution in beef liver where branched and cyclic alkanes are predominant. The enrichment and the similarity of the n-alkane distribution in the fatty tissues on heart and in pasture plants may have implications for the physiological aspects of hydrocarbons in the diet.

Alkanes↗
PubMed1975

Abiotic, Graphitic Microstructures in Micaceous Metaquartzite about 3760 Million Years Old from Southwestern Greenland: Implications for Early Precambrian Microfossils.

An Early Precambrian micaceous metaquartzite subjected to low to moderate metamorphism in the Isua area of Southwestern Greenland was derived from the erosion of preexisting rocks which were probably sialic in composition. This metaquartzite may have been formed before the emergence of life. It contains globular particles of graphite arranged in narrow veins or along foliation or bedding planes. This rock contains no organic compounds besides traces of methane and no biologically significant elements associated with the graphite microstructures. Reaction of primitive methane with ferric oxides appears to have oxidized the methane to the vein graphite and reduced the ferric oxides to ferrous-ferric oxide (magnetite). The graphitic microstructures are likely to be abiotic in origin, although a biological origin is not impossible. Somewhat younger microstructures found in other locations on earth have often been described as microfossils; this origin should be reexamined on the basis of the above mentioned conclusions.

Journal Article↗
PubMed1975

Stereoisomeric specificity and soil gas disequilibria: implications for martian life detection.

Variations in the atmospheric composition of soil samples were monitored by mass spectrometry after the addition of mixtures of D- and L-carbohydrates and/or amino acids. The changes in concentrations of CO2 in these experiments were found to be related to the steroisomeric configurations of the compounds with which the soil samples were enriched. The potential of this relationship provides a comparatively simple approach for detecting life in extraterrestrial soils.

Amino Acids↗
PubMed1975

Comparison of the survival and metabolic activity of psychrophilic and mesophilic yeasts subjected to freeze-thaw stress.

A mesophilic yeast, Candida utilis, and a psychrophilic yeast, Leucosporidium stokesii, were subjected to freeze-thaw cycling over the range 25 to -60 C. Viability after freeze-thaw stress was directly correlated with the rate of cooling and the physiological age of the cultures. Rates of glucose fermentation and oxidation could be directly correlated with viability. The optimal cooling rate for both yeast strains was 4.5 to 6.5 C/min; however, their levels of survival obtained at this optimal cooling rate varied considerably. In addition, the psychrophile was less resistant to freeze-thaw stress than was the mesophile.

Basidiomycota↗