Fig. 5. Catalytic activity of H34 with inserted Pro95 (H34-Pro95(+)): reaction profiles for FRET-PD-1 substrate cleavage were investigated for up to 78 h of reaction time using H34 and H34-Pro⁹⁵(+). The catalytic activity of the H34-Pro⁹⁵(+) mutant was substantially reduced relative to H34 lacking Pro⁹⁵.