Figure 27.

Narrow-bore nanoelectrospray ionization emitters with inner tip diameters less than 1000 nm can be used to obtain more accurate K_d values for carbonic anhydrase (P) inhibitors (L). (a–d) nESI mass spectra of aqueous solutions containing 5 μM human carbonic anhydrase I, 2 μM ethoxzolamide, and 70 mM ammonium acetate obtained using emitter tips with inner diameters of (a) ∼2000, (b) ∼850, (c) ∼500, and (d) ∼250 nm. (e) K_d values measured using nESI as a function of the emitter tip diameter for the binding of ethoxzolamide (squares), brinzolamide (circles), furosemide (triangles), and dichlorphenamide (diamonds) to human carbonic anhydrase I. Reproduced from ref (435). Copyright 2019 American Chemical Society.