Impact of Tryptophan Oxidation in Complementarity-Determining Regions of Two Monoclonal Antibodies on Structure-Function Characterized by Hydrogen-Deuterium Exchange Mass Spectrometry and Surface Plasmon Resonance.

Purpose: Tryptophan's (Trp) unique hydrophobic and structural properties make it an important antigen binding motif when positioned in complementarity-determining regions (CDRs) of monoclonal antibodies (mAbs). Oxidation of Trp residues within the CDR can deleteriously impact antigen binding, particularly if the CDR conformation is altered. The goal of this study was to evaluate the conformational and functional impact of Trp oxidation for two mAb subtypes, which is essential in determining the structure-function relationship and establishing appropriate analytical control strategies during protein therapeutics development.

Concentrations and distribution of some polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in an ombrotrophic peat bog profile of Switzerland.

An efficient method was developed for the analysis of selected PCBs and PAHs in dry peat samples. The method includes a shaking extraction using acetone and hexane followed by the purification of the crude extract by gel permeation chromatography (GPC) which turned out to be the key clean-up step. The method was used to determine seven indicator PCBs and 16 EPA-PAHs in individual sections of an ombrotrophic peat core in south-west Switzerland.