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Drug-to-Antibody Ratio/Protein Conjugation

Drug antibody ratio (DAR) is an important parameter of antibody drug conjugates (ADC) and refers to the average drug to antibody ratio for a given preparation of ADC. The significance of DAR in biotherapeutics is a primarily as a measure of drug loading for an ADC. Using a combination of intact mass measurement of the ADC as well as peptide mapping, an accurate DAR can be determined with site localization.​


Figure 1. Workflow for drug-to-antibody/protein conjugation ratio calculation.

Figure 2. Comparison of Sigma-mAb to Sigma-ADC following conjugation.