NATIVE FLUORESCENCE DETECTION AND SPECTRAL DIFFERENTIATION OF PEPTIDES CONTAINING TRYPTOPHAN AND TYROSINE IN CAPILLARY ELECTROPHORESIS

A native fluorescence detection system for capillary electrophoresis i s described that achieves low attomole detection limits and simultaneo us acquisition of complete fluorescence emission spectra. The system i s designed for detection of peptides through the intrinsic fluorescenc e of tryptophan and tyrosine residues. The detection system employs a frequency doubled krypton laser operating at 284 Mn for excitation, a sheath now cell, a reflective f/1.2 microscope objective, an imaging s pectrograph, and a CCD detector. The detection capabilities are charac terized with tryptophan and tyrosine, which have limits of detection ( 3 sigma) of 2 x 10(-10) and, 2 x 10(-8) M, respectively. Acquisition o f the fluorescence emission spectrum provides the ability to distingui sh three classes of peptides: those that contain tryptophan, those tha t contain tyrosine, and those that contain both tryptophan and tyrosin e.