Sequence determinants of protein aggregation in human VH domains.

Human antibody variable heavy (VH) domains tend to aggregate upon denaturation, for instance, by heat or acid. We have previously demonstrated that domains resisting protein aggregation can be selected from CDR-only repertoires by phage display. Here we analysed their sequences to identify determinants governing protein aggregation. We found that, while many different CDR sequences conferred aggregation-resistance, certain physico-chemical properties were strongly selected for. Thus, hydrophobicity and beta-sheet propensity were significantly lower among the selected domains, whereas net negative charge was increased. Our results provide guidelines for the design of human VH repertoires with reduced levels of protein aggregation.