Study on the complexes of egg-white lysozyme and beta-cyclodextrin by electrospray ionization time-of-flight mass spectrometry

Electrospray ionization time-of-flight mass spectrometry is a good tool for the characterization of noncovalent complexes because of "soft" ionization and condition. Under our experimental conditions, the nonspecific noncoval ent interactions of egg-white lysozyme with beta -cyclodextrin have been ob served by electrospray ionization/time - of - flight mass spectrometry. Som e mass spectrometic features, such as ion abundance enhancement by selectin g appropriate nozzle potential, and stoichimetries, show that the noncovale nt complexes between lysozyme and beta -cyclodextrin have been formed at a ratio of 1:1,1:2, 1:3 in higher concentration and almost left ratio 1:1 in lower concentration of beta -cyclodextrin. These results imply that the com plexes should be nonspecific complexes. Tn addition, we founded that the ap propriate condition, such as addition of some organic solvent or suitable S CIEX chamber temperature, is conductive to the ionization of noncovalent co nplexes.