Inhibition of ADAMTS-4 and ADAMTS-5 by TIMP-3 and N-TIMP-3. ADAMTS5-1 (A, 0.5 nM) and ADAMTS5-5 (B, 0.5 nM) were incubated with 0.5-5 nM TIMP-3 ( ) or N-TIMP-3 (➃) for 1 h at 37°C and residual activity against Abz-TESE∼SRGAIY-Dpa-KK determined (18 h, 37°C). TIMP-3 and N-TIMP-3 had Ki(app) values of 0.70 ± 0.04 nM and 0.14 ± 0.02 nM respectively for ADAMTS5-1, and 1.89 ± 0.06 nM and 1.35 ± 0.04 nM respectively for ADAMTS5-5. ADAMTS4-1 (C, 0.5 nM) and ADAMTS4-4 (D, 0.5 nM) were incubated with 0.25-10 nM TIMP-3 ( ) or N-TIMP-3 (➃) for 1 h at 37°C and residual activity against FAM-AE∼LQGRPISIAK-TAMRA (1 μM) determined (18 h, 37°C). TIMP-3 and N-TIMP-3 had Ki(app) values of 0.39 ± 0.03 nM and 0.19 ± 0.04 nM respectively for ADAMTS4-1, and 0.38 ± 0.04 nM and 0.55 ± 0.05 nM respectively for ADAMTS4-4. The error values given are the standard errors on the fit of the data to the tight binding equation (equation 2) (Bieth, 1995).