Table 3. Inhibition constants (K_i) of MMP1_CAT and MMP10_CAT with N-TIMP2 selective variants.

	Ki* (nM)		Fold change of Ki**		Specificity shift
Clone	MMP1CAT	MMP10CAT	MMP1CAT	MMP10CAT	MMP1CAT	MMP10CAT
N-TIMP2WT	0.7 ± 0.1	3.5 ± 0.8
N-TIMP214_17	0.92 ± 0.15	3.2 ± 0.4	0.8	1.1	212#	154#
N-TIMP29_13	18 ± 8	40 ± 14	0.04	0.08	10+	5+

^*K_i values (nM) of the purified variants were obtained by fitting the experimental data to Morrison's tight binding equation (Eq. 1).

^**Fold change of Ki reflects the ratio between the K_i of N-TIMP2_WT and the K_i of an N-TIMP2 variant.

^# For the MMP14-inhibiting clone N-TIMP2_{14_17}, specificity shifts were calculated as the ratio between the fold improvement to MMP14_CAT, as compared to MMP1_CAT and MMP10_CAT (the specificity shift is defined as the fold change of K_i for MMP14/fold change of Ki for MMPX, where X designates either MMP1_CAT or MMP10_CAT).

⁺ For the MMP9-inhibiting clone N-TIMP2_{9_13}, specificity shifts were calculated as the ratio between the fold of improvement to MMP9_CAT in comparison to MMP1_CAT and MMP10_CAT (the specificity shift is defined as the fold change of K_i for MMP9/fold change of Ki for MMPX, where X designates either MMP1_CAT or MMP10_CAT).