Evidence for enzymatic activity in the absence of solvent in gas-phase complexes of lysozyme and oligosaccharides

Hen egg-white lysozyme complexed to substrate and nonsubstrate oligosaccharides are examined by electrospray ionization mass spectrometry. Heated capillary dissociation and collision induced dissociation (CID) are used to characterize the complexes. The relative order of stability obtained in gas phase agrees well with their solution-phase association constants. A proton transfer reaction occurs during the CID of substrate complexes that is not observed with non-substrate complexes. Oligosaccharide fragments are also observed with lysozyme-chitohexaose complex during CD. The possibility of lysozyme activity in the gas phase, or a gas-phase enzymatic activity, is explored. (C) 1999 Elsevier Science B.V.