Interactions between (parts of) two biomolecule chains (e.g. base pairing in deoxyribonucleic acid (DNA) double helix, or the interactions between two polypeptide chains, or between a DNA and a protein molecule).
Source: PAC, 2018, 90, 1121. 'Terminology of bioanalytical methods (IUPAC Recommendations 2018)' on page 1185 (https://doi.org/10.1515/pac-2016-1120)