Recombinant proteins became essential components of drug manufacturing. Quality control of such proteins is routine task, which usually requires a lot of time, expensive reagents, specialized equipment and highly educated personnel. In this study we propose a new concept for protein purity evaluation that is based on application of bio-assisted potentiometric multisensor system. The model object for analysis was recombinant protein A from Staphylococcus aureus (SpA), which is commonly used for monoclonal antibody purification. SpA solutions with different amount of host cell related impurities (Escherichia coli, bacterial lysate) were analyzed. Two different bio-transducers were employed: proteinase K from Tritirachium album and baker's yeast Saccharomyces cerevisiae. It was shown that both bio-transducers are able to induce changes in pure and lysate-contaminated SpA samples. Different products of yeast digestion and proteolysis with proteinase of pure SpA and lysate were detected with size exclusion high-performance liquid chromatography (SE-HPLC). The induced changes of chemical composition are detectible with potentiometric multisensor system and can be related to SpA purity through projection on latent structures (PLS) regression technique. The proposed method allows for estimation of the impurity content with 12% accuracy using proteinase K and 16% accuracy using baker's yeast. The suggested approach could be useful for early contamination warning at initial protein purification steps. The analysis requires no expensive materials and equipment, no bio-material immobilization, and its duration time is comparable with other commonly used methods like chromatography or electrophoresis though the main part of this time is related to the sample preparation.
Keywords: Baker's yeast; Potentiometric sensor; Protein A; Protein purity; Proteinase K.
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