Deuterium incorporation curves of four peptides. HDX data for the apo xylanase is represented by the open square, and HDX data for the xylanase interacting with xylohexaose substrate is represented with the closed square. A. HDX data for peptide ‘VGWTTGSSAPINF’ containing residues from 38 to 50. B. HDX data for peptide ‘YTIWENTRVNEPSIQGTAT’ containing residues from 102 to 120. C. HDX data for peptide ‘SVYGWSTNPLVEY’ containing residues from 64 to 76, D. HDX data for peptide ‘SVYGWSTNPLVEYY’ containing residues from 64 to 77.