The presence of extensive reciprocal conformational freedom between the catalytic and the hemopexin-like domains of full-length matrix metalloproteinase-1 (MMP-1) is demonstrated by NMR and small angle x-ray scattering experiments. This finding is discussed in relation to the essentiality of the hemopexin-like domain for the collagenolytic activity of MMP-1. The conformational freedom experienced by the present system, having the shortest linker between the two domains, when compared with similar findings on MMP-12 and MMP-9 having longer and the longest linker within the family, respectively, suggests this type of conformational freedom to be a general property of all MMPs.