FIGURE 5.

Residues of HPX-1 implicated in collagen binding by mutagenesis and assay. Orthogonal views of the crystal structure of MMP-1* are shown as a ribbon diagram with the left-hand side in the same orientation as that in Fig. 3A. Mutated HPX-1 residues are shown as sticks and colored according to the collagen binding activity of the mutant, i.e. Phe³⁰¹, Val³¹⁹, and Asp³³⁸ in red (K_d ≥ 24 μm); Tyr³⁰⁹, Arg³³⁷, and Pro³⁶¹ in green (16 μm < K_d < 24 μm); and Arg³⁰⁰, Ser³¹⁸, Pro³²⁵, Gln³⁵⁴, and His³⁵⁸ in blue (K_d ≤ 16 μm). Residues Ile²⁹⁰ and Arg²⁹¹, previously identified as an exosite (29), are shown as magenta sticks.