PHOTO-EXCITATION NATURE OF AROMATIC AMINO ACIDS UNDER ELECTRIC FIELD: A FLUORESCENCE SPECTROSCOPY STUDY

J. PENDHARKAR*, M. WAGHMARE**, PUSHPINDER G. BHATIA***, B. KHADE**, P. DONGRE**#

*”K.J. Somaiya” College, Mumbai-400077, India

**Department of Biophysics, University of Mumbai, Mumbai 400098, Maharashtra, India

***Department of Physics, Guru Nanak College of ASC Mumbai-400037, India

This study demonstrates the effect of the external electric field during the real-time photoexcitation process in tryptophan and tyrosine under the steady-state fluorescence. The electric field was applied from 1.0 to 12 V/cm during photoexcitation by xenon flash lamp. The tryptophan intensity increased gradually and reached double at 6 V/cm, and at higher voltages, up to 12 V/cm, the intensity decreased with redshift (357 to 363 nm). In the case of tyrosine, the intensity was decreased with increasing voltage. There was no change in λmax in UV absorption spectra. The interesting observation was a two-fold increase in the quantum yield of tryptophan. The obtained results are promising and new, and would be useful in improving fluorescence technology in molecular imaging and characterization of fluorophores.

Key words: Fluorescence spectroscopy, tryptophan, tyrosine, electric field.

Corresponding author’s e-mail: drpmdongre@yahoo.co.in

 

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