Article Abstract:
Site-directed mutagenesis was used to develop various forms of streptokinase with a longer functiuonal half-life. Mutant proteins of streptokinase were produced by the Bacillus subtilis secretory production system, which retained comparable kinetics parameters in plasmogen activation and showed different degrees of plasma resistance depending on the nature of mutation. These results indicate that plasma-resistant forms of streptokinase can be engineered without affecting their activity. Moreover, engineering of streptokinase with a longer in vitro functional half-life requires blockage of the N-terminal cleavage site.
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Article Abstract:
Cytoplasmic glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from the group A streptococcal strain 64/14 was isolated and examined to determine whether it is related to the plasmin receptor protein (Plr) of strain 64/14 purified from mutanolysin extract and to recombinant Plr. This was triggered by the significant similarity of Plr to GAPDHs. No differences were found between Plr and cytoplasmic GAPDH in terms of antibody reactivity, plasmin-binding activity, GAPDH activity, N-terminal amino acid sequence, peptide map analysis and amino acid composition analysis.
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Article Abstract:
Genetic mutagenesis methods were used to investigate the role of the putative plasmin receptor protein Plr in the plasmin-binding phenotype of group A streptococci. Results showed that a C-terminal lysyl residue was needed for wild-type levels of plasmin binding. Moreover, while lowered plasmin-binding activity was observed in mutated proteins expressed in Escherichia coli, glyceraldehyde-3-phosphate dehydrogenase activity was preserved.
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