Statistical characteristics in primary structures of functional regions of Escherichia coli genome. I. Frequency characteristics

Analysis of the frequencies of occurrence of mono- and dinucleotides in sequenced E. coli DNA fragments was performed. The DNA sequences of total length 135 000 nucleotides were considered. It was demonstrated that the fragments of DNA which have different functional properties also have different parameters of neighbour nucleotides correlation. Moreover, periodical positional dependence of correlation parameters in coding regions was found. The evolution significance of stated observation is discussed, so as the opportunity of using them in the special model of nucleotide's sequences, which is needed for development of the computer recognition algorithms for genomic functional units.     

Stability of the alpha-helix structure of oligopeptides

The problem of stabilization of oligopeptide alpha-helix conformation is discussed. The stabilizing role of intramolecular H-bonds and coulombic interactions for single molecules was shown. The influence of media results in the competition for formation of inter and intramolecular H-bonds and for coulombic interactions. High competitive media, eg. water, diminishes alpha-helix stability.     

Effect of rate of increase of water temperature on sensitivity of fish digestive glycosidases to action of copper and zinc

There was established an increase of sensitivity of glycosidases of intestinal mucosa of juvenile goldfish Carassius auratus, carp Cyprinus carpio, roach Rutilus rutilus, and common perch Perca fluviatilis to action in vitro of heavy metal ions (copper and zinc at concentrations of 0.1–25 mg/l) at heating of water at the summer period. The inhibitory effect of copper and zinc ions as a rule was higher at the heating rate of 50°C/h than at the rate of 4°C/h. The perch glycosidases were less sensitive to the elevation of temperature and to effect of the copper ions as compared with the enzymes of the carp species.