The modified asparaginase Was79 was derived from the recombinant wild-type L-asparaginase of Wolinella succinogenes. The Was79 contains the amino acid substitutions V23Q and K24T responsible for the resistance to trypsinolysis and the N-terminal heparin-binding peptide KRKKKGKGLGKKR responsible for the binding to heparin and tumor K562 cells in vitro. When tested on a mouse model of Fischer lymphadenosis L5178Y, therapeutic efficacy of Was79 was significantly higher than that of reference enzymes at all single therapeutic doses used (125-8000 IU/kg). At Was79 single doses of 500-8000 IU/kg, the complete remission rate of 100 % was observed. The Was79 variant can be expressed intracellularly in E. coli as a less immunogenic formyl-methionine-free form at high per cell production levels.

Protein nanoparticles (NPs) can be used as vaccine platforms for target antigen presentation. Aim: To conduct a proof-of-concept study to demonstrate that an effective NP platform can be built based on a short self-assembling peptide (SAP) rather than a large self-assembling protein. Materials & methods: SUMO-based protein fusions (SFs) containing an N-terminal SAP and a C-terminal antigen were designed, expressed in Escherichia coli and purified. The structure was investigated by electron microscopy. The antibody response was tested in mice after two adjuvant-free immunizations. Results: Renatured SFs form fiber-like NPs with the antigen exposed on the surface and induce a significant antibody response with a remarkably high target-to-platform ratio. Conclusion: The platform is effective and has considerable potential for modification toward various applications, including vaccine development.

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The capacity of yeast to produce the highly active variants of PLA2 has been confirmed. The high-active variants were based on the original enzyme from the strain А-2688 of Streptomyces violaceoruber. To reduce the enzyme toxicity and to increase its expression, various approaches were tested including point mutations, construction of artificial N- and/or C-end pro-regions, hybridization with other proteins and engineering or inactivation of glycosylation sites. As a main result, the modified PLA2 enzymes were obtained which have the same secretion level as their low-active predecessors, but specific activity of which was at least tenfold higher. As the main feature, the selected mutants were characterized by a lower affinity for Ca2+ that probably accounts for their low toxicity (and high expression capacity) at the stage of biosynthesis and their ability to activate under special conditions, e.g. during the egg yolk fermentation. The data obtained can provide a basis for the cost reduction of highly active PLA2 enzyme preparations in industries where the application of high calcium concentrations is allowed. recombinant phospholipase А2, Streptomyces violaceoruber, yeasts, secretion, producer strain The work was initiated by the Innovation Center Biriuch - New Technologies, Ltd., and was supported within the framework of the State Assignment no. 595-00004-18 PR.