Confirming Structure Of Antibody-Based Drugs

Antibody-based drugs are on the rise. Because subtle structural changes can alter their specificity, there’s a need for analytical methods that ensure that antibody-based drugs have the desired structure. A new way to characterize the disulfide bonds that hold antibodies together could help fill that need, reported Brandon T. Ruotolo of the University of Michigan, Ann Arbor. In the method, Ruotolo and his coworkers select an individual charge state of a gas-phase antibody and heat it via gas-phase collisions, which cause it to unfold. They measure the size of the unfolded states with ion mobility. By measuring the unfolding products as a function of the collisional heating, they can track the unfolding trajectory for the intact antibody. The number and size of the unfolded species form a fingerprint that is unique to the original isolated ion. By comparing the gas-phase unfolding for an analyte antibody to that of a reference antibody, the researchers can quickly determine whether they match. Such a method could be used as a quality-control tool to make sure that an antibody drug has the correct structure.