Аннотация:In the current work, bacteriolytic activity of serotransferrin was
discovered. Although transferrins have been known for a long
time, some of their functions are not completely clear. There is
the information that transferrins can suppress the bacterial
growth, however, bacteriolytic activity of these proteins has not
been described before. In our experiments, human blood plasma
proteins were separated to identify and study new bacteriolytic
factors. It was found that the protein fraction with molecular
weights between 60 and 80 kDa showed bacteriolytic activity on
bacteria cells. After a few stages of chromatography the active
protein was purified. Trypsinolysis of the isolated protein followed
by mass spectrometry analysis allowed us to identify this
protein as a serotransferrin. Purified serotransferrin demonstrates
bacteriolytic activity against Escherichia coli, Micrococcus luteus,
Bacillus subtilis and Bacillus megaterium cells. pH profiles of
activity are characterized at a maximum pH of 8.7–8.9. At an
optimal pH value (8.8), the rates of lysis of various bacteria in
the presence of serotransferrin and lysozyme were compared,
considering the rate of lysis as a percentage of “lysozyme activity
against E. coli”. Lysozyme at a concentration of 0.3 lg/mL acts
effectively against E. coli (100%) and M. luteus (68%), less efficiently
against B. subtilis (18%) and practically does not act at
all against B. megaterium (1%). Serotransferrin at a concentration
of 3 lg/mL acts effectively against E. coli (61%), less efficiently
against M. luteus and B. subtilis (13% and 12%), but
relatively efficiently against B. megaterium (23%). The detailed
investigation of serotransferrin bacteriolytic properties can be
useful in drug-design to fight antibiotic-resistant pathogenic
microorganisms. The authors thank Dr Marina Serebryakova,
leading researcher of the Belozersky Institute of Physico-Chemical
Biology, for conducting a mass spectrometric study.