Characterization of fluorescein isothiocyanate. II. Absorption and fluorescence after conjugation to human- and rabbit-gamma-globulin and bovine serum albumin.

The alteration of extinctions of both FITC isomers by coupling to bovine serum albumin, human, and rabbit-gamma-globulin were studied. The extinction coefficients of these FTC conjugates were established. The emission characteristics of the FITC isomers and their conjugates were investigated under conditions normaly used in fluorescence microscopy. FITC I was found as the most suitable marker for human- and rabbit-gamma-globulin. In contrast the fluorescence of FTC II-BSA conjugates is stronger than that of the corresponding FTC I-BSA conjugate.