With two sequences providing 100% conversion, we designed monobody CS_NC which contains "DAIPENLPPL" at the N-terminus and the "ENL" moiety at the C-terminus (Figure and Table ). The bioconjugation reaction with 2 equivalents of dansylcadaverine amine led to 98% conversion to the double conjugated product. No starting material could be identified; the remaining 2% corresponding with the single conjugated product (Figure , Tables and). A similar behavior was obtained with the monobody CS_2C which contains at the Cterminus the reactive sequence "DAIPENLPPL", a linker composed of four "A" amino acids and the "ENL" sequence. With two equivalents of amine, 93% conversion towards the double conjugated product was obtained (Figures , Tables S1, S2 and 1). For both sequences, an excess of the amine reagent did not lead to a higher number of conjugated products (data not shown), confirming the specificity of the conjugation.