Melittin and the 8-26 fragment. Differences in ionophoric properties as measured by monolayer method.

Melittin is a major (approximately 50%) protein component of bee venom. This peptide is an amphiphilic protein, because, while the amino acid residues 1-20 are predominantly hydrophobic (with the exception of Lys-7), residues 21-26 are hydrophilic. The binding properties to vesicles and lipid bilayers of melittin have provided much useful information regarding biological (hemolytic) activity (Habermann, E., 1972, Science [Wash. DC], 177:314-322). Recent studies have convincingly established that the melittin monolayer (at air-water interface) model membrane system allows one to analyze the various forces present in such structures. We present comparative monolayer studies of melittin and the peptide fragment 8-26 regarding the channel formation for the selective anion (Cl-) penetration in monolayers, analogous to melittin (tetramer) channel function in lipid bilayer. The differences in surface pressure and surface potential of monolayers between native melittin and the 8-26 fragment suggest that these may be ascribed to Lys-7

Buffer Effects in Submersed Denitrifying Biofilter

The high content of nitrates in drinking water leads to serious diseases. The creation of biofiltering devices with the longest time of their operation between preventive flushes is extremely important. The purpose of this study was to investigate the features of the functioning of the developed U-shaped submersible denitrifying biofilter during its long-term operation in the piston filtration mode. The denitrification of water by using the method of displacement (piston) biofiltration in a submersible small U-shaped biofilter with immovable carriers of attached microflora in its filter load was studied. As a result, clogging of the pore space of the biofilter in the zone of excess bacterial nutrition is prevented and the vital activity of bacteria is maintained in places where there is no nutrient substrate. It has been shown that, due to adaptive mechanisms, denitrifying bacteria convert nitrate ions into gaseous nitrogen, consuming extracellular polymeric substances. The rate constants of the reaction of reduction of nitrates to molecular nitrogen in different zones of the biofilter under different filtration modes were determined. The activity of the microflora inside the biofilter quickly returns to its original level when a full-fledged external nutrition is resumed. The efficiency of nitrate to nitrogen conversion in the studied biofilter is 94.2±8.9%