Effect of Fluorescent Dye Labeling on Electrospray Ionization Efficiency of Peptides and Proteins

摘要

We studied the ionization efficiency of fluorescently labeled peptides and proteins. The separation of 4 peptides was successfully achieved using HPLC. FITC-labeled and unlabeled peptides and protein were also separated by HPLC. Labeling leads to higher protonation of peptides than in the absence of the label as shown by triply-charged ionization state of bradykinin acetate. Labeling of lysozyme with FITC also increases the average charge state of the protein. Further experiments are underway to label peptides and proteins with other fluorescent dyes and exactly quantitate the amounts of labeled and unlabeled polypeptides. These experiments will enable precise measurement of the influence of the dye labeling on the ESI efficiency of polypeptides.