Fig. 4.
Munc18 and syntaxin 1 from M. brevicollis interact with nanomolar affinity. Calorimetric titrations of syntaxin 1 into Munc18 from M. brevicollis. Syx1 (1-279) binds Munc18 with higher affinity and enthalpy than Syx1 (20-279), indicating that the N-peptide participates in binding. The graph displays the integrated areas normalized to the amount of the injectant (kcal·mol−1) versus its molar ratio to Munc18. The solid lines represent the best fit to the data for a single binding site model. The raw data are shown in Fig. S3.