The Effect of Resonance Energy Homotransfer on the Intrinsic Tryptophan Fluorescence Emission of the Bothropstoxin-I Dimer

2001 ◽  
Vol 284 (4) ◽  
pp. 1011-1015 ◽  
Author(s):  
A.H.C. de Oliveira ◽  
J.R. Giglio ◽  
S.H. Andrião-Escarso ◽  
R.J. Ward
Keyword(s):  
Fluorescence Emission ◽  
Resonance Energy ◽  
Tryptophan Fluorescence ◽  
Intrinsic Tryptophan Fluorescence

Synthesis and solution conformation of [Trp1, Val5]-angiotensin II

1977 ◽  
Vol 55 (1) ◽  
pp. 75-82 ◽  
Author(s):  
Peter W. Schiller
Keyword(s):  
Angiotensin Ii ◽  
Solid Phase ◽  
Fluorescence Emission ◽  
Resonance Energy ◽  
Tryptophan Fluorescence ◽  
Exchange Chromatography ◽  
Phase Method ◽  
Aqueous Environment ◽  
Solution Conformation ◽  
Intramolecular Distance

[Trp1, Val5]-Angiotensin II was synthesized by the solid-phase method and purified by partition chromatography on Sephadex G-25 and by ion-exchange chromatography on Sephadex SP-25. Relative to [Val5]-angiotensin II, the analog displayed 36% smooth muscle activity in a preparation of the superior mesenteric artery. Conformational aspects of the analog were revealed by fluorescence techniques. The fluorescence emission maximum at 350 nm suggests a completely aqueous environment for the tryptophanyl residue in [Trp1, Val5]-angiotensin II. Singlet–singlet resonance energy transfer between Tyr in position 4 and Trp in position 1 was evaluated for a calculation of the intramolecular distance between these two residues on the basis of the Förster equation. From the relative increase of tryptophan fluorescence a transfer efficiency of > 0.9 was obtained, which is compatible with the observed complete quenching of tyrosine fluorescence in the analog. The computed average intramolecular distance of < 8 Å precludes an extended conformation for the N-terminal sequence encompassing residues 1 through 4 at neutral pH and suggests the existence of a loop in this part of the molecule. The results are discussed in relation to the various models proposed for the solution conformation of angiotensin II.

scholarly journals Preparation of CdTe/Alginate Textile Fibres with Controllable Fluorescence Emission through a Wet-Spinning Process and Application in the Trace Detection of Hg2+ Ions

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 570 ◽  
Author(s):  
Zhihui Zhao ◽  
Cunzhen Geng ◽  
Xihui Zhao ◽  
Zhixin Xue ◽  
Fengyu Quan ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Resonance Energy Transfer ◽  
Fluorescence Emission ◽  
Resonance Energy ◽  
Coagulation Bath ◽  
Wet Spinning ◽  
Trace Detection ◽  
Metallic Ions ◽  
Textile Fibres ◽  
Cdte Nanocrystals

Fluorescent textile fibres (FTFs) are widely used in many industrial fields. However, in addition to fibres with good fluorescence, fibres with excellent colour controllability, structural stability and appropriate mechanical strength still need to be developed. In this work, CdTe/alginate composite FTFs are prepared by taking advantage of the interactions between CdTe nanocrystals (NCs) and alginate macromolecules via a wet-spinning machine with a CaCl2 aqueous solution as the coagulation bath. CdTe NCs were chemically fixed in the fibre due to the interactions among surface ligands, macromolecules and coagulators (calcium ions), which ensured the excellent dispersity and good stability of the fibres. Förster resonance energy transfer (FRET) between NCs in the fibre was found to be restricted, which means that the emission colour of the fibres was totally controllable and could be predicted. Other properties of alginate fibres, such as flame retardance and mechanical strength, were also well preserved in the fluorescent fibres. Finally, FTFs showed good selectivity toward trace Hg2+ ions over other metallic ions, and the detection could be identified by the naked eye.

scholarly journals Inactivation of sarcoplasmic-reticulum Ca2+-ATPase in low-frequency-stimulated muscle results from a modification of the active site

1992 ◽  
Vol 285 (1) ◽  
pp. 303-309 ◽  
Author(s):  
S Matsushita ◽  
D Pette
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Active Site ◽  
Low Frequency ◽  
Fluorescein Isothiocyanate ◽  
Tryptophan Fluorescence ◽  
Atp Binding ◽  
Binding Characteristics ◽  
Intrinsic Tryptophan Fluorescence ◽  
Inactive Form ◽  
Induced Changes

Molecular changes underlying the partial inactivation of the sarcoplasmic-reticulum (SR) Ca(2+-) ATPase in low-frequency-stimulated fast-twitch muscle were investigated in the present study. The specific Ca(2+)-ATPase activity, as well as the ATP- and acetyl phosphate-driven Ca2+ uptakes by the SR, were reduced by approx. 30% in 4-day-stimulated muscle. Phosphoprotein formation of the enzyme in the presence of ATP or Pi was also decreased to the same extent. Measurements of ATP binding revealed a 30% decrease in binding to the enzyme. These changes were accompanied by similar decreases in the ligand-induced (ATP, ADP, Pi) intrinsic tryptophan fluorescence. A decreased binding of fluorescein isothiocyanate (FITC) corresponded to the lower ATP binding and phosphorylation of the enzyme. Moreover, Pi-induced changes in fluorescence of the FITC-labelled enzyme did not differ between SR from stimulated and contralateral muscles, indicating that Ca(2+)- ATPase molecules which did not bind FITC were responsible for the decreased Pi-dependent phosphorylation, and therefore represented the inactive form of the enzyme. No differences existed between the Ca(2+)-induced changes in the intrinsic fluorescence of SR from stimulated and contralateral muscles which fit their similar Ca(2+)-binding characteristics. Taking the proposed architecture of the Ca2(+)-ATPase into consideration, our results suggest that the inactivation relates to a circumscribed structural alteration of the enzyme in sections of the active site consisting of the nucleotide-binding and phosphorylation domains.

scholarly journals Substrate-induced conformational transition in human phenylalanine hydroxylase as studied by surface plasmon resonance analyses: the effect of terminal deletions, substrate analogues and phosphorylation

2003 ◽  
Vol 369 (3) ◽  
pp. 509-518 ◽  
Author(s):  
Anne J. STOKKA ◽  
Torgeir FLATMARK
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Phenylalanine Hydroxylase ◽  
Conformational Transition ◽  
Tryptophan Fluorescence ◽  
Catalytic Core ◽  
Intrinsic Tryptophan Fluorescence ◽  
Human Phenylalanine Hydroxylase ◽  
Activity State

The optical biosensor technique, based on the surface plasmon resonance (SPR) phenomenon, was used for real-time measurements of the slow conformational transition (isomerization) which occurs in human phenylalanine hydroxylase (hPAH) on the binding/dissociation of l-phenylalanine (l-Phe). The binding to immobilized tetrameric wt-hPAH resulted in a time-dependent increase in the refractive index (up to approx. 3min at 25°C) with an end point of approx. 75RU (resonance units)/(pmolsubunit/mm2). By contrast, the contribution of binding the substrate (165Da) to its catalytic core enzyme [ΔN(1—102)/ΔC(428—452)-hPAH] was only approx. 2RU/(pmolsubunit/mm2). The binding isotherm for tetrameric and dimeric wt-hPAH revealed a [S]0.5-value of 98±7μM (h = 1.0) and 158±11μM, respectively, i.e. for the tetramer it is slightly lower than the value (145±5μM) obtained for the co-operative binding (h = 1.6±0.4) of l-Phe as measured by the change in intrinsic tryptophan fluorescence. The responses obtained by SPR and intrinsic tryptophan fluorescence are both considered to be related to the slow reversible conformational transition which occurs in the enzyme upon l-Phe binding, i.e. by the transition from a low-activity state ('T-state') to a relaxed high-activity state ('R-state') characteristic of this hysteretic enzyme, however, the two methods reflect different elements of the transition. Studies on the N- and C-terminal truncated forms revealed that the N-terminal regulatory domain (residues 1—117) plus catalytic domain (residues 118—411) were required for the full signal amplitude of the SPR response. Both the on- and off-rates for the conformational transition were biphasic, which is interpreted in terms of a difference in the energy barrier and the rate by which the two domains (catalytic and regulatory) undergo a conformational change. The substrate analogue 3-(2-thienyl)-l-alanine revealed an SPR response comparable with that of l-Phe on binding to wild-type hPAH.

scholarly journals Different modes of interaction of pulmonary surfactant protein SP-B in phosphatidylcholine bilayers

1997 ◽  
Vol 327 (1) ◽  
pp. 133-138 ◽  
Author(s):  
Antonio CRUZ ◽  
Cristina CASALS ◽  
Kevin M. W. KEOUGH ◽  
Jesús PÉREZ-GIL
Keyword(s):  
Aqueous Phase ◽  
Protein Interactions ◽  
Pulmonary Surfactant ◽  
Fluorescence Emission ◽  
Tryptophan Fluorescence ◽  
Egg Yolk ◽  
Surfactant Protein ◽  
Scanning Calorimetry ◽  
Adsorption Activity ◽  
Egg Yolk Phosphatidylcholine

Pulmonary surfactant-associated protein B (SP-B) has been incorporated into vesicles of dipalmitoyl phosphatidylcholine (DPPC) or egg yolk phosphatidylcholine (PC) by two different procedures to characterize the dependence of lipid–protein interactions on the method of reconstitution. In method A the protein was dissolved in a small volume of either methanol or 60% (v/v) acetonitrile and injected into an aqueous phase containing phospholipid vesicles. In method B the vesicles were prepared by injection of a mixture of phospholipid and SP-B dissolved in methanol or aqueous acetonitrile. Both methods of reconstitution led to the extensive interaction of SP-B with PC bilayers as demonstrated by co-migration during centrifugation, marked protection against proteolysis, change in the fluorescence emission intensity of SP-B, and protection of SP-B tryptophan fluorescence from quenching by acrylamide. SP-B promoted the rapid adsorption of DPPC on an air/liquid interface irrespective of the method of protein reconstitution. However, the interfacial adsorption activity of SP-B reconstituted by method B remained stable for hours, but that of SP-B prepared by method A decreased with time. Electron microscopy showed that the injection of SP-B into an aqueous phase containing PC or DPPC vesicles (method A) induced a rapid aggregation of vesicles. By contrast, a much longer time was required for detecting vesicle aggregation when the protein was reconstituted by co-injection of SP-B and phospholipids (method B). The presence of 5% (w/w) SP-B in DPPC bilayers prepared by method B broadened the differential scanning calorimetry thermogram and decreased the enthalpy of the transition. In contrast, the injection of SP-B into preformed DPPC vesicles (method A) did not influence the gel-to-liquid phase transition of DPPC bilayers. Taken together, these results indicate that the mode and extent of interaction of SP-B with surfactant phospholipids depends on the conditions of preparation of lipid/protein samples, and that care should be taken in the interpretation of findings from reconstituted systems on the role of these surfactant proteins in the alveolar space.

scholarly journals Intrinsic tryptophan fluorescence spectroscopy reliably determines galectin-ligand interactions

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Paulina Sindrewicz ◽  
Xiaoxin Li ◽  
Edwin A. Yates ◽  
Jeremy E. Turnbull ◽  
Lu-Yun Lian ◽  
...  
Keyword(s):  
Fluorescence Spectroscopy ◽  
Tryptophan Fluorescence ◽  
Intrinsic Tryptophan Fluorescence ◽  
Ligand Interactions

scholarly journals An intrinsic-tryptophan-fluorescence study of phage phi29 connector/nucleic acid interactions

1994 ◽  
Vol 225 (2) ◽  
pp. 747-753 ◽  
Author(s):  
Maria Angeles Urbaneja ◽  
Susana Rivas ◽  
Jose L. Carrascosa ◽  
Jose Maria Valpuesta
Keyword(s):  
Nucleic Acid ◽  
Tryptophan Fluorescence ◽  
Fluorescence Study ◽  
Intrinsic Tryptophan Fluorescence ◽  
Nucleic Acid Interactions

Unfolding and Conformational Studies on Bovine Adrenodoxin Probed by Engineered Intrinsic Tryptophan Fluorescence†

Biochemistry ◽  
2002 ◽  
Vol 41 (36) ◽  
pp. 11008-11016 ◽  
Author(s):  
Frank Hannemann ◽  
Aloke Kumar Bera ◽  
Birgitta Fischer ◽  
Michael Lisurek ◽  
Klaus Teuchner ◽  
...  
Keyword(s):  
Tryptophan Fluorescence ◽  
Conformational Studies ◽  
Intrinsic Tryptophan Fluorescence
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