Identification of potential sites for tryptophan oxidation in recombinant antibodies using tert-butylhydroperoxide and quantitative LC-MS.

Amino acid oxidation is known to affect the structure, activity, and rate of degradation of proteins. Methionine oxidation is one of the several chemical degradation pathways for recombinant antibodies. In this study, we have identified for the first time a solvent accessible tryptophan residue (Trp-32) in the complementary-determining region (CDR) of a recombinant IgG1 antibody susceptible to oxidation under real-time storage and elevated temperature conditions.

[A method of quality assurance of dynamic wedges].

Background: One of the important prerequisites for using a virtual wedge is the availability of an appropriate method for quality assurance. A simple method to determine wedge angles has been developed.

Material And Methods: A formula based on the exponential attenuation curve has been derived, that allows for the calculation of the wedge isodose angles based on 2 measurement points perpendicular to the central ray.