Figure 1.

Activity of tetrameric β-tryptase with different WT to S195A protomer ratios. A, cartoon depicting the generation of β-tryptase tetramers following enterokinase cleavage of WT and S195A zymogens at four different zymogen mixing ratios (Ratio^ZM). The heterotetramers are actually a mixture of individual tetramer species weighted according to their binomial distribution (Table 1). B, comparison of the four β-tryptase tetramers with different protomer ratios at 1 nm measured with the chromogenic substrate S-2288. Data were collected in triplicate and fit to the Michaelis-Menten equation; errors are shown as S.D. C, comparison of V_max and K_m values of the different β-tryptase tetramer mixtures with WT; V_max and K_m were normalized to 100% for WT; errors are shown as S.D.