Complex analysis of medical products containing streptokinase using mass-spectromertry

The possibility of mass-spectrometry using for complex analysis of medical products containing streptokinase is showed. The protein composition and target protein - streptokinase - content are determined. The identification and quantitative estimation of streptokinase content were carrying out by MALDI-MS on exhaustive tryptic cleavage products. For the quantitative estimation, 18O-isotopic tracers of streptokinase tryptic peptides with known concentration were added to the analysis samples as internal standard. The analyzable protein concentration was calculated on the intensities ratio of isotopic distribution of the analyzable protein and 18O labeled internal standard. The streptokinase biological activity was estimated by its capability to activate plasminogen in human blood serum. The plasminogen activation is accompanied by the appearance of esterase activity which was determined by the cleavage rate of synthetic substrate TAME. The formation of hydrolytic cleavage product TA was determined with ESI-MS in the presence of radio labeled TA as an internal standard. All isotope tracers used as internal standards were obtained by isotopic exchange of products containing carboxyl (peptides and tozilarginin) in the medium H218O.