A method for capturing a saxiphilin to allow for detection, characterisation, isolation an/or purification of said saxiphilin or its ligand, comprising: (1) providing a PST conjugate comprising a PST moiety bound via a linker through a site other than the binding site for saxiphilin directly or indirectly to a biotin moiety; (2) exposing the PST conjugate to a sample putatively containing said saxiphilin to create a reaction mixture and to (strept)avidin; and (3) allowing binding through the PST moiety to the saxiphilin and through the biotin moiety to (strept)avidin to form a captured PST complex.