Table 2.

AdoHcy k_on and k_off rates for WT and Y68A COMT at 5 °C

Rate	WT	Y68A
kon (M−1s−1)*	8.4 ± 2.1 × 105	925 ± 226
koff (min−1)†	264 ± 78	8 ± 2
kcat (min−1)	2.47 ± 0.03	(0.09 ± 0.02)‡

^*The k_on is derived from the slope of the fitting of k_obs of stopped-flow fluorescence quenching vs. [AdoHcy].

^†The k_off = K_d × k_on.

^‡The value of k_cat for Y68A is approximate; see Discussion.