IDENTIFICATION OF RECOMBINANT HUMAN LYSOZYME AT THE PICOMOLE LEVEL BY ELECTROSPRAY-LC/MS

The identification of recombinant human lysozymes containing a large amount of sodium salts has been carried out by means of the on-line coupling of microbore high-performance liquid chromatography with electrospray ionization mass spectrometry. The addition of 0.05-0.1 % TFA to the LC mobile phase was necessary for the retention of the mutants on the column and for the separation of the salts in the sample solution. The reduction in ESI efficiency on account of the presence of TFA was overcome by the gradient of TFA in simultaneous with that of acetonitrile. The molecular weights of the mutants obtained by consuming a sample amount of low-picomole level were in agreement with those calculated within an error range of 1-2 Da.