Characterization of the two tryptophan residues of the lactose repressor from Escherichia coli by phosphorescence and optical detection of magnetic resonance. 1993

L E Burns, and A H Maki, and R Spotts, and K S Matthews
Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77251.

The native lactose repressor from Escherichia coli (Lac Rep) and two single-point mutants, W220Y and W201Y, were investigated using low-temperature phosphorescence and optical detection of magnetic resonance (ODMR) spectroscopy. Emission from two tryptophan residues was evident in the phosphorescence spectrum of native Lac Rep at 77 K. Using the single-point mutants, the triplet-state properties of tryptophans 201 and 220 were obtained independently. Trp 220 was characterized as a partially solvent-exposed residue (0,0 band centered at 409.5 nm), while tryptophan 201 exhibited the properties of a buried residue (0,0 band centered at 413.5 nm). Both single-point mutant proteins experienced changes in tryptophan triplet-state properties as a result of binding either of two inducer sugars: isopropyl beta-D-thiogalactoside, a monosaccharide, or melibiose, a disaccharide. Putative singlet-singlet energy transfer from tryptophan 220 to tryptophan 201 was also investigated, but the quantitative results must be viewed with some caution.

UI MeSH Term Description Entries
D007544 Isopropyl Thiogalactoside A non-metabolizable galactose analog that induces expression of the LAC OPERON. IPTG,Isopropyl 1-Thio-beta-D-galactopyranoside,1-Thio-beta-D-galactopyranoside, Isopropyl,Isopropyl 1 Thio beta D galactopyranoside,Thiogalactoside, Isopropyl
D008027 Light That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range. Light, Visible,Photoradiation,Radiation, Visible,Visible Radiation,Photoradiations,Radiations, Visible,Visible Light,Visible Radiations
D008163 Luminescent Measurements Techniques used for determining the values of photometric parameters of light resulting from LUMINESCENCE. Bioluminescence Measurements,Bioluminescent Assays,Bioluminescent Measurements,Chemiluminescence Measurements,Chemiluminescent Assays,Chemiluminescent Measurements,Chemoluminescence Measurements,Luminescence Measurements,Luminescent Assays,Luminescent Techniques,Phosphorescence Measurements,Phosphorescent Assays,Phosphorescent Measurements,Assay, Bioluminescent,Assay, Chemiluminescent,Assay, Luminescent,Assay, Phosphorescent,Assays, Bioluminescent,Assays, Chemiluminescent,Assays, Luminescent,Assays, Phosphorescent,Bioluminescence Measurement,Bioluminescent Assay,Bioluminescent Measurement,Chemiluminescence Measurement,Chemiluminescent Assay,Chemiluminescent Measurement,Chemoluminescence Measurement,Luminescence Measurement,Luminescent Assay,Luminescent Measurement,Luminescent Technique,Measurement, Bioluminescence,Measurement, Bioluminescent,Measurement, Chemiluminescence,Measurement, Chemiluminescent,Measurement, Chemoluminescence,Measurement, Luminescence,Measurement, Luminescent,Measurement, Phosphorescence,Measurement, Phosphorescent,Measurements, Bioluminescence,Measurements, Bioluminescent,Measurements, Chemiluminescence,Measurements, Chemiluminescent,Measurements, Chemoluminescence,Measurements, Luminescence,Measurements, Luminescent,Measurements, Phosphorescence,Measurements, Phosphorescent,Phosphorescence Measurement,Phosphorescent Assay,Phosphorescent Measurement,Technique, Luminescent,Techniques, Luminescent
D008553 Melibiose A disaccharide consisting of one galactose and one glucose moiety in an alpha (1-6) glycosidic linkage.
D008956 Models, Chemical Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment. Chemical Models,Chemical Model,Model, Chemical
D009682 Magnetic Resonance Spectroscopy Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING). In Vivo NMR Spectroscopy,MR Spectroscopy,Magnetic Resonance,NMR Spectroscopy,NMR Spectroscopy, In Vivo,Nuclear Magnetic Resonance,Spectroscopy, Magnetic Resonance,Spectroscopy, NMR,Spectroscopy, Nuclear Magnetic Resonance,Magnetic Resonance Spectroscopies,Magnetic Resonance, Nuclear,NMR Spectroscopies,Resonance Spectroscopy, Magnetic,Resonance, Magnetic,Resonance, Nuclear Magnetic,Spectroscopies, NMR,Spectroscopy, MR
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
D004735 Energy Transfer The transfer of energy of a given form among different scales of motion. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed). It includes the transfer of kinetic energy and the transfer of chemical energy. The transfer of chemical energy from one molecule to another depends on proximity of molecules so it is often used as in techniques to measure distance such as the use of FORSTER RESONANCE ENERGY TRANSFER. Transfer, Energy
D004926 Escherichia coli A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc. Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
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

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