NSP inhibition by N-arylacyl O-sulfonated aminoglycosides. (A–C) Dose-dependent inhibition of HNE by neomycin, kanamycin and apramycin derivatives, respectively; (D–F) dose-dependent inhibition of CatG by neomycin, kanamycin and apramycin derivatives, respectively; (G–I) dose-dependent inhibition of Pr3 by neomycin, kanamycin and apramycin derivatives, respectively. Absorbance of p-nitroaniline released from a protease specific chromogenic substrate was measured at 405 nm and normalized to enzyme only control. Nonlinear regression curve fitting was performed to obtain IC50 values summarized in Table I. Data are presented as mean ± SE (n = 3). This figure is available in black and white in print and in color at Glycobiology online.