Fig. 1. Properties of dibromopyridazinediones (diBrPDs) and the structure of PD 1. (a) diBrPDs can be used to functionally rebridge antibodies. Incorporation of a clickable handle in their design enables attachment of a fluorophore or drug, represented by a star; (b) chemical structure of PD 1 with a strained alkyne handle; (c) chemical structure of Alexa FluorTM 488 (fluorophore) bearing an azide handle.
