HX-MS reveals allosteric effects on the metalloprotease domain by antispacer antibodies. Deuterium incorporation of MDTCS fragments is measured over the time course of 21 hours with or without antibody bound. Incorporation in the absence of scFvs is depicted in green circles and dashed lines; incorporation of deuterium in the presence of scFvs is depicted in red circles and solid lines. The y-axis indicates the number of deuterium atoms incorporated over time on the x-axis.