The Steady-State and Decay Characteristics of Protein Tryptophan Fluorescence from Algae

The intrinsic steady-state fluorescence due to tryptophan has been obtained from monospecific cultures of fourteen plankton algae of various genera. Fluorescence decay profiles of protein tryptophan residues were obtained for eight marine plankton algae. Each organism exhibits a strong maximum in its emission spectrum at 320–340 nm when excited at 290 nm. Iodide quenching and denaturization experiments with 8 M urea provide strong evidence for the assignment of the 320–340 nm fluorescence to protein tryptophan. Most importantly, the decay of this bacterial protein tryptophan fluorescence has been described. The observation that characteristic protein-tryptophan fluorescence lifetimes have been obtained for each organism suggests that measurements of fluorescence lifetimes may be helpful in the rapid characterization of algae. Direct application will likely be found in combination with the measurement of other luminescence parameters.