The Spatial Structure of the ACTH-(7–10) Molecule

Biophysics - The spatial structure of the ACTH-(7–10) molecule, a 7–10 fragment of the adrenocorticotropic hormone, with the Phe–Arg–Trp–Gly amino-acid sequence was...     

Synthesis of heat-shock proteins in Saccharomyces cerevisiae protoplasts

The effect of cellular capsule elimination in Saccharomyces cerevisiae yeasts (protoplast formation) on the heat-shock protein synthesis and the synthesis of the proteins in protoplasts were studied. The methods of mono- and dimeric electrophoresis have demonstrated that (1) about 18 heat-shock proteins with the molecular masses 26-98 Kd are synthesized in cells at 41 degrees C; (2) protoplast formation per se does not induce the synthesis of heat-shock proteins, but the induction of these proteins in protoplasts at 41 degrees C is similar to the one in intact cells. The protoplast formation induces the synthesis of specific proteins different from heat-shock proteins and the synthesis is inhibited by the heat-shock. The heat-shock induces modification of 88 and 86 Kd heat-shock proteins. It inhibits the synthesis of a number of peptides (15-50 Kd) in cells and protoplasts.     

Purification and properties of two endonucleases specific for apurinic/apyrimidinic sites in DNA from Saccharomyces cerevisiae

Two distinct endonucleases from Saccharomyces cerevisiae, specific for apurinic/apyrimidinic sites (AP-endonucleases A and B), have been extensively purified and characterized. Both are free from unspecific and ultraviolet-specific endonucleases and exonucleases. The two enzymes are monomeric proteins of around 24 000 daltons. Both are sensitive to ionic strength and most active in the presence of 150 and 100 mM NaCl for AP-endonucleases A and B, respectively. They are not absolutely dependent on divalent cations, since they are insensitive to EDTA, although AP-endonuclease A is activated by Ca²⁺ or Mg²⁺ and AP-endonuclease B by Mg²⁺ only. ATP inhibits the enzymes. AP-endonuclease A reacts optimally between pH 6 and 8, and AP-endonuclease B at pH 8. AP-endonuclease A is more stable at 60°C (half-life of 17 min) than B (half-life of 4 min). AP-endonucleuase A is insensitive to N-ethylmaleimide or ρ-chloromercuribenzoate. AP-endonuclease B is also insensitive to N-ethylmaleimide, but ρ-chloromercuribenzoate inhibits its activity.     

Petsamomyces, a new genus of organic-walled microfossils from the coal-bearing deposits of the Early Proterozoic, Kola Peninsula

A new genus of organic-walled microfossils of supposed fungal origin, Petsamomyces Belova gen. nov., is described from the black shales of the Pechenga complex of the Early Proterozoic (Kola Peninsula). The find testifies to the development of eukaryotic heterotrophic microorganisms as early as 2 Ga ago.     

Genetic aspects of microphylogeny of black-and-white cattle of Uzbekistan

The genetic aspects of microphylogeny of herds of black and white cattle of Asian and European populations have been studied on the basis of distribution analysis of frequency in 62 antigens of 11 systems of blood groups.     

Multiple increase in productivity of the yeast at reducing the fraction of D<Subscript>2</Subscript>O in water

We found a two-fold increase in the productivity of baker’s yeast grown on a nutrient mixture prepared in light water with a D₂O content (127 ppm) smaller than in the distilled water (150 ppm). The number of water monomers that provides the biosynthetic activity (water transport through membrane channels) of yeast cells with an increased CO₂ yield was determined for the first time. We established that the selectivity of cell membrane channels in water of different composition depends not only on the motion of ortho-and para-spin H₂O isomers in solution, as was shown earlier, but also on the concentration of D₂O.