Accepted_test

The cleavage of N-terminal initiator methionine (iMet) from the polypeptide chain is the main co- and post-translational modification, covering up to 80% of the cell proteome, which is carried out by specific enzymes - methionine aminopeptidases (MAP). A significant problem in the biotechnology of producing recombinant proteins, with their heterologous expression in E. coli, is the incomplete removal of iMet, which leads to incorrect protein folding (aggregation, amyloidization), changes in their half-life, loss of activity, immunogenicity, etc. To solve this problem, the technology of processing target recombinant proteins with MAP enzymes is used, both in vitro and using co-expression. MAPs from different organisms are metal-dependent proteases and have similar three-dimensional folding, but differ in substrate specificity and operating conditions. Currently available commercial MAPs from humans, E. coli and P. furiosus do not provide the full variety of specificities and conditions required in the biotechnology of removing iMet from recombinant proteins. In this regard, the search for new MAPs that are stable under “non-standard” conditions (elevated temperatures, pH, in the presence of denaturants, etc.) is relevant. The purpose of this work was to study the substrate specificity of a new MAP from the bacterium Thermus thermophilus (Tth-MAP) using synthetic peptides.