Biomaterial Database

Fluorescence quenching studies of Trp repressor using single-tryptophan mutants. 1995

Z Blicharska, and Z Wasylewski

Department of Physical Biochemistry, Jagellonian University, Kraków, Poland.

Time-resolved and steady-state fluorescence have been used to resolve the heterogeneous emission of single-tryptophan-containing mutants of Trp repressors W19F and W99F into components. Using iodide as the quencher, the fluorescence-quenching-resolved spectra (FQRS) have been obtained The FQRS method shows that the fluorescence emission of Trp99 can be resolved into two component spectra characterized by maxima of fluorescence emission at 338 and 328 nm. The redder component is exposed to the solvent and participates in about 21% of the total fluorescence emission of TrpR W19F. The second component is inacessible to iodide, but is quenched by acrylamide. The tryptophan residue 19 present in TrpR W99F can be resolved into two component spectra using the FQRS method and iodide as a quencher. Both components of Trp19 exhibit similar maxima of emission at 322-324 nm and both are quenchable by iodide. The component more quenchable by iodide participates in about 38% of the total TrpR W99F emission. The fluorescence lifetime measurements as a function of iodide concentration support the existence of two classes of Trp99 and Trp19 in the Trp repressor. Our results suggest that the Trp aporepressor can exist in the ground state in two distinct conformational states which differ in the microenvironment of the Trp residues.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D011193	Potassium Iodide	An inorganic compound that is used as a source of iodine in thyrotoxic crisis and in the preparation of thyrotoxic patients for thyroidectomy. (From Dorland, 27th ed)	Antistrumin,Ioduro Potasico Rovi,Iosat,Jod beta,Jodetten Henning,Jodgamma,Jodid,Jodid Hexal,Jodid Verla,Jodid dura,Jodid-ratiopharm,Mono-Jod,Pima,SSKI,Thyro-Block,Thyroprotect,Iodide, Potassium,Jodid ratiopharm,Mono Jod,Thyro Block
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D012097	Repressor Proteins	Proteins which maintain the transcriptional quiescence of specific GENES or OPERONS. Classical repressor proteins are DNA-binding proteins that are normally bound to the OPERATOR REGION of an operon, or the ENHANCER SEQUENCES of a gene until a signal occurs that causes their release.	Repressor Molecules,Transcriptional Silencing Factors,Proteins, Repressor,Silencing Factors, Transcriptional
D001426	Bacterial Proteins	Proteins found in any species of bacterium.	Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial
D013050	Spectrometry, Fluorescence	Measurement of the intensity and quality of fluorescence.	Fluorescence Spectrophotometry,Fluorescence Spectroscopy,Spectrofluorometry,Fluorescence Spectrometry,Spectrophotometry, Fluorescence,Spectroscopy, Fluorescence
D014364	Tryptophan	An essential amino acid that is necessary for normal growth in infants and for NITROGEN balance in adults. It is a precursor of INDOLE ALKALOIDS in plants. It is a precursor of SEROTONIN (hence its use as an antidepressant and sleep aid). It can be a precursor to NIACIN, albeit inefficiently, in mammals.	Ardeydorm,Ardeytropin,L-Tryptophan,L-Tryptophan-ratiopharm,Levotryptophan,Lyphan,Naturruhe,Optimax,PMS-Tryptophan,Trofan,Tryptacin,Tryptan,Tryptophan Metabolism Alterations,ratio-Tryptophan,L Tryptophan,L Tryptophan ratiopharm,PMS Tryptophan,ratio Tryptophan