PDBsum entry 1kwl

Plant protein

PDB id

1kwl

Contents

			Protein chains

					29 a.a.


					86 a.a.

References listed in PDB file

Key reference

Title

Dielectric relaxation in a single tryptophan protein.

Authors

M.Ghose, S.Mandal, D.Roy, R.K.Mandal, G.Basu.

Ref.

FEBS Lett, 2001, 509, 337-340. [DOI no: 10.1016/S0014-5793(01)03202-1]

PubMed id

11741613

Abstract

Although dielectric relaxation can significantly affect the intrinsic fluorescence properties of a protein, usually it is fast compared to fluorescence timescales and needs to be slowed down by adding viscogens or lowering temperature before its impact on fluorescence can be studied. We report here a remarkable blue shift in fluorescence upon bimolecular quenching in the single-tryptophan thermostable protein Bj2S, the 2S seed albumin from Brassica juncea, at ambient temperature and viscosity. The magnitude of the blue shift ( approximately 5 nm at 50% quenching by acrylamide) is striking in a single-tryptophan protein and is attributed to a slowly relaxing dielectric environment in Bj2S from red edge excitation, steady-state polarization and time-resolved fluorescence experiments. Our results have important implications on interpretation of fluorescence of proteins with highly constrained backbones and in designing model systems for studying slow protein solvation dynamics using Trp fluorescence as the reporter probe.



	Figure 1. Fig. 1. Acrylamide-quenched fluorescence spectra of Bj2S (295 nm excitation) showing a progressive blue shift in λ[max] with increasing concentration of acrylamide (acrylamide concentration for the most quenched spectrum is 0.26 M). Center of gravity of emission, λ[cg] (integrated λ[em]-weighted normalized fluorescence intensity), as a function of acrylamide concentration for 295 (○), 298 ( triangle, open ) and 300 ( open ) nm excitation are shown in the inset.		Figure 4. Fig. 4. Temperature-dependent Bj2S fluorescence spectra excited at 280 nm (solid line) and 295 nm (broken line).