Fluorescence quenching

Silver nanoparticles (Ag NPs) with a size of around 9 nm were fabricated and quantified through fluorescence quenching of rhodamine B (RhB). A series of solutions composed of RhB with various concentrations of Ag NPs ranging from 0.09 pM to 0.98 pM were prepared, and optical properties were investigated by absorption and fluorescence spectroscopies.

8p viengfa 28-10-2024 3 2   Download

The binding of Thermomyces lanuginosa lipase and its mutants [TLL(S146A), TLL(W89L), TLL(W117F, W221H, W260H)] to the mixed micelles of cis-parinaric acid/ sodium taurodeoxycholate at pH 5.0 led to the quenching of the intrinsic tryptophan fluorescence emission (300–380 nm) and to a simultaneous increase in the cis-parinaric acid fluorescence emission (380–500 nm). These findings were used to characterize the Thermomyces lanuginosa lipase/cisparinaric acid interactions occurring in the presence of sodium taurodeoxycholate....

9p system191 01-06-2013 49 5   Download

We report the recombinant neurolysin and thimet oligo-peptidase (TOP) hydrolytic activities towards internally quenched fluorescent peptides derived from the peptide Abz-GGFLRRXQ-EDDnp (Abz,ortho-aminobenzoicacid; EDDnp,N-(2,4-dinitrophenyl) ethylenediamine), in which X was substituted by 11 different natural amino acids. Neurolysin hydrolyzed these peptides at R–R or at R–X bonds, and TOP hydrolyzed at R–R or L–R bonds, showing a preference to cleave at three or four amino acids from the C-terminal end. ...

9p research12 23-04-2013 44 3   Download

Recent crosslinking studies indicated the localization of the coupling ion binding site in the Na + -translocating F1F0 ATP synthase ofIlyobacter tartaricus within the hydrophobic part of the bilayer.Similarly, a membrane embedded H + -binding site is accepted for the H + -trans-locating F1F0 ATP synthase ofEscherichia coli.For a more definite analysis, we performed parallax analysis of fluorescence quenching with ATP synthases from both I. tartaricus and E. coli.

9p tumor12 22-04-2013 26 2   Download

Intravenous iron, used for the treatment of anemia in chronic renal failure andother diseases, represents a possible source of free iron in tissue cells, particularly in the liver. In this study we examined the effect of different sources of intravenous iron (IVI) on the labile iron pool (LIP) which represents the nonferritin-bound, redox-active iron that is implicated in oxidative stress and cell injury. Furthermore, we examined the role of the LIP for the synthesis of ferritin.

8p tumor12 20-04-2013 48 4   Download

Cyclic AMP receptor protein (CRP) regulates the expression of more then 100 genes inEscherichia coli. It is known that the allosteric activation of CRP by cAMP involves a long-distance signal transmission from the N-ter-minal cAMP-binding domain to the C-terminal domain of CRP responsible for the interactions with specific sequences of DNA. In this report we have used a CRP mutant containing a single Trp13 located in the N-terminal domain of the protein.

14p awards 05-04-2013 42 4   Download

The structural properties of EspB, a virulence factor of theEscherichia coli O157 type III secretion system, were characterized. Far-UV and near-UV CD spectra, recorded between pH 1.0 and pH 7.0, show that the protein assumesa-helical structures and that some tyrosine tertiary contacts may exist. All tyrosine side-chains are exposed to water, as determined by acryl-amide fluorescence quenching spectroscopy.

13p awards 05-04-2013 27 4   Download

A molecular understanding of volatile anesthetic mechanisms of action will require structural descriptions of anesthetic–protein complexes. Porcine odorant binding protein is a 157 residue member of the lipocalin family that features a large b-barrel internal cavity (515 ± 30 A ˚ 3 ) lined predomin-antly by aromatic and aliphatic residues. Halothane binding to theb-barrel cavity was determined using fluorescence quenching of Trp16, and a com-petitive binding assay with 1-aminoanthracene.

0p awards 05-04-2013 18 2   Download

We have used fluorescence quench titrations, EPR spectroscopy and steady-state kinetics to study the effects of site-directed mutants of FrdB, FrdC and FrdD on the proximal menaquinol (MQH2) binding site (QP)of Escherichia colifumarate reductase (FrdABCD) in cytoplasmic membrane preparations. Fluorescence quench (FQ) titrations with the fluorophore and MQH2 analog 2-n-heptyl-4-hydroxyquinoline-N-oxide (HOQNO) indi-cate that the QPsite is defined by residues from FrdB, FrdC and FrdD. In FQ titrations, wild-type FrdABCD binds HOQNO with an apparentKdof 2.

14p awards 05-04-2013 39 3   Download

The recombinant cysteine peptidases, cruzain from Trypanosoma cruziand CPB2.8DCTE fromLeishmania mexicana, are cathepsin L-like and characteristically endo-peptidases. In this study, we characterized the carboxydi-peptidase activities of these enzymes and compared them with those of human recombinant cathepsin B and cathep-sin L. The analysis used the internally quenched fluorescent peptide Abz-FRFK*-OH and some of its analogues, where Abz isortho-aminobenzoic acid and K* is (2,4-dinitrophe-nyl)-e-NH2-lysine. ...

8p dell39 03-04-2013 35 5   Download

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Fluorescence Manipulation by Gold Nanoparticles: From Complete Quenching to Extensive Enhancement

13p toshiba25 08-12-2011 35 4   Download

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học General Psychiatry cung cấp cho các bạn kiến thức về ngành y đề tài: Assessment of tissue oxygen tension: comparison of dynamic fluorescence quenching and polarographic electrode technique...

5p thulanh16 22-10-2011 48 3   Download