A complex lipid preparation was obtained by extraction of soybean flour with organic solvents. This preparation was shown to include not only phospholipids (major components), but also up to 30% saponins. These compounds were identified by TLC, HPLC, and 1H-NMR spectroscopy. Minor components of the lipid extract were represented by polypeptides associated with phospholipids via electrostatic or hydrophobic forces.
Seasonal changes in the content of alginic acid and fucoidan have been studied in four species of fucus algae from the Barents sea: Fucus vesiculosus, F. distichus, F. serratus, and Ascophyllum nodosum. These polysaccharides are accumulated in the biomass of the algae during summer and autumn. To ensure complete processing of fucus algae it is recommended that the raw material be harvested within this period.
The survival of pure cultures of Rhizobium leguminosarum bv. pisum and Rhizobium trifolii and their interaction with associative diazotrophic and phosphate-mobilizing bacteria after inoculation of sterile soil were studied. The viable heterotypical diazotrophic and rhizobial phosphate-mobilizing association was shown to be formed whose efficiency was 14% (clover) and 28% (pea) higher compared to monorhizobial inoculates.
Inhibition of soybean urease by polymeric substrate analogues, urea and thiourea polydisulfides (PDSU and PDSTU, respectively), or three thiophosphoric acid amides (TPAA), tri-(N-3-hydroxyphenyl)thiophosphamide (1), tri-(N-4,4'-aminodiphenyl)thiophosphamide, and di-oxy-(N-alpha-piridyl)thiophosphamide (3) was studied in aqueous solutions at various pH values. The inhibitory effects of all these substances were reversible and competitive with the lowest inhibition constant Ki 2.8 microM for TPAA-1 at pH 3.85. Above and below this pH value, Ki increased reaching 24 [mu]M at pH 7.2. All test substances inhibited urease comparably with known inhibitors such as thiols (cysteamine, etc.) and hydroxamic acid derivatives, but were less efficient than phosphorodiamidates. Structural features of possible urease inhibitors of higher efficiency were proposed.
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