The laser scanning confocal microscopy has been a powerful tool in research of protein crystal growth, which requires the protein to be extrinsically fluorescent. According to our laser source (488 nm Ar⁺), fluorescein-5-isothiocyanate (FITC) was used as a probe to label the lysozyme. The absorption fluorescence spectra of the labeled lysozyme indicate that FITC has little effect on the biological and chemical characteristics of lysozyme. So the FITC derivatives of lysozyme can be used in research of protein crystal growth by the laser scanning confocal microscopy utilizing 488 nm laser source.

Key words: fluorescein-5-isothiocyanate, lysozyme, fluorescence characterization, crystal growth