An RNA aptamer possessing a novel monovalent cation-mediated fold inhibits lysozyme catalysis by inhibiting the binding of long natural substrates

Effect of Lys1.2minE on catalytic activity of lysozyme. (A) Crystal structure of Lys1.2minE–lysozyme complex depicting the active site catalytic residues (Glu35 and Asp52) of lysozyme in black and the aptamer binding interface in gray. (B) Lysozyme activity against M. lysodeikticus cell walls. The turbidity (OD₄₅₀) from the cell wall material remaining after 60 min in the presence of 0.3 μM lysozyme is shown for increasing aptamer stoichiometries. (C) MALDI-TOF activity assay monitoring lysozyme hydrolysis of chitopentaose after 15 min in the absence and presence of equimolar Lys1.2minE.