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C-Terminal Lysine Assessment

Creative Biolabs has established a platform to predict a series of post-translational modifications (PTM) of therapeutic proteins, such as antibodies, blood factors, hormones and interferons. C-terminal Lysine processing is a very common PTM and occur in the bioprocessing caused by the action of basic carboxypeptidases. The heterogeneity of the antibody charge and mass is mostly caused by C-terminal Lysine processing, resulting in antibody products as species with one, two or no Lysines.


C-Terminal Lysine

Human IgG heavy chain genes usually encode a C-terminal lysine. However, this residue is mostly missing in the endogenous antibodies isolated from serum, while some low but variable level of C-terminal lysine is present on therapeutic antibodies expressed in mammalian cell culture systems. Whether the mass and charge heterogeneity caused by C-terminal Lysine processing affect antibody bioactivity or safety profile is still unknown.

The level of the Lysine processing varies as process condition changes and each species should be monitoredand kept within predefined limits. It is sufficient to carefully control the process parameters and conditions. Since C-terminal Lysines are naturally cleaved off and do not effect the potency or safety of the antibody candidate, they can be simply removed by protein engineering. Creative Biolabs can provide you the vectors of human IgG genes without C-terminal Lysine’s presence.

As Lysine contains a positive charge, antibodies lacking the basic C-terminal lysine(s) differ in the charge state from the ones with lysine. The distribution of lysine variants (none, one or two lysines) can be determined by ion-exchange chromatography, such as analysis with a ProPac WCX-10 weak cation-exchange column for the high-resolution separation of different antibody isoforms. Creative Biolabs guarantees  that all the antibodies are characterized experimentally in house within 2-3 weeks as customer desires.

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