A bifunctional activity label 1c has been constructed for the selection of active β-lactamases displayed on filamentous bacteriophage. It features an original 6-sulfonylamido-penam sulfone moiety, as β-lactamase suicide-inhibitor, and a biotinyl residue, for separation by affinity chromatography, connected through a linker including a cleavable disulfide bond. The inhibitor 28 resulted from coupling of methoxymethyl 6-aminopenicillinate 8 with N- ...