Figure 7.

Stoichiometry of wild-type and variant crmA inhibition of elastase. Porcine pancreatic elastase (50 nM) was incubated with the indicated molar ratios of wild-type (•) or P1 Arg (▴) crmAs for 1 h or 15 min, respectively. Residual elastase activity was then measured by 10-fold dilution into 50 μM succinyl-Ala-Ala-Ala-7-amido-4-methylcoumarin and monitoring the initial rate of substrate cleavage at 380 nm excitation and 440 nm emission wavelengths. Solid lines are linear regression fits of the data.