Cystine Knot Peptides with Tuneable Activity and Mechanism

Knottins are topologically complex peptides that stabilised by a cystine knot and have exceptionally diverse functions, including protease inhibition. However, approaches for tuning their activity in situ limited. Here, we demonstrate separate the of knottin inhibitors using light or streptavidin. We show inhibitory selectivity an engineered can be controlled with activating second mode action switches inhibitor ON against new targets. Guided library screen, also identify position inhibitor's binding loop permits insertion biotin tag without impairing activity. Using streptavidin, biotinylated knottins nanomolar affinity switched OFF assays, anticoagulant factor XIIa rapidly human plasma. Our findings expand scope precisely controlling protein function.