Figure 3
Determination of the tautomeric state of the active site histidines. See reference [18] for further details on interpretation of the results. Blue: Due to partially overlapping H2-C2 signals the protonation state determination yielded only an average value of the two peaks. The value suggests that the histidines are in deprotonated state. The Suc-AEPF-p NA titration however separated the two H2-C2 signals and enabled separate determination of the protonation states. Red: Unique assignment is not available, but the protonation state determination gives equivalent results for both peaks.