Journal ArticleDOI
Exposure of tryptophanyl residues in proteins. Quantitative determination by fluorescence quenching studies.
TLDR
The value of this probing technique lies in its ability to sense not only the steady-state exposure of a residue in a protein, but also its dynamic exposure.Abstract:
Acrylamide is an efficient quencher of tryptophanyl fluorescence which we report to be very discriminating in sensing the degree of exposure of this residue in proteins. The quenching reaction involves physical contact between the quencher and an excited indole ring, and can be kinetically described in terms of a collisional and a static component. The rate constant for the collisional component is a kinetic measure of the exposure of a residue in a protein, and values ranging from 4 X 10(9) M-1 S-1 for the fully exposed tryptophan in the polypeptide, adrenocorticotropin, to less than 5 X 10(8) M-1 S-1 for the buried residue in azurin have been found. Static quenching is readily detected in proteins that are denatured, or contain only a single fluorophor. Quenching patterns for most multi-tryptophan containing proteins are difficult to analyze precisely, but qualitative information can, nevertheless, be extracted. Applications of this probing technique for monitoring protein conformational changes, such as the acid-induced expansion of human serum albumin, and inhibitor binding to enzymes, are presented. The value of this method lies in its ability to sense not only the steady-state exposure of a residue in a protein, but also its dynamic exposure.read more
Citations
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Lipid association-induced N- and C-terminal domain reorganization in human apolipoprotein E3.
TL;DR: Biophysical evidence is provided that, in addition to reported conformational changes in the four-helix bundle configuration induced by lipid association, lipid binding of apoE is accompanied by reorientation of the tertiary disposition of the NT and CT domains.
Journal ArticleDOI
Localization and environment of tryptophans in soluble and membrane-bound states of a pore-forming toxin from staphylococcus aureus
TL;DR: A shorter average lifetime of tryptophans in the membranes-bound alpha-toxin as compared to the native toxin supported the conclusions based on iodide quenching of the membrane-bound toxin.
Journal ArticleDOI
Tryptophan 512 is sensitive to conformational changes in the rigid relay loop of smooth muscle myosin during the MgATPase cycle.
TL;DR: The conformation of the rigid relay loop containing Trp-512 is altered upon MgATP hydrolysis and during the transition from weak to strong actin binding, establishing a communication pathway from the active site to the actin-binding and converter/lever arm regions of myosin during muscle contraction.
Journal ArticleDOI
Consequences of poly-glutamine repeat length for the conformation and folding of the androgen receptor amino-terminal domain.
TL;DR: The view that the presence and length of the poly-Q repeat modulate the folding and structure of the AR-NTD is supported, as this polypeptide showed enhanced binding of the hydrophobic probe 8-anilinonaphthalene-1-sulphonic acid but was more sensitive to urea-induced unfolding.
Journal ArticleDOI
Structural changes in human tear lipocalins associated with lipid binding
TL;DR: It is postulate that TL, exposed to the steep surface pH gradient that exists at lipid-aqueous interfaces, would release lipid in association with a molten globule transition, suggesting a plausible regulatory mechanism for lipid delivery from lipocalins at the tear film surface.
References
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Journal ArticleDOI
The interpretation of protein structures: estimation of static accessibility.
B. Lee,Frederic M. Richards +1 more
TL;DR: The accessibility of atoms in the twenty common amino acids in model tripeptides of the type Ala-X-Ala are given for defined conformation and the larger non-polar amino acids tend to be more “buried” in the native form of all three proteins.
Journal ArticleDOI
Removal of Fatty Acids from Serum Albumin by Charcoal Treatment
TL;DR: Fluorescence spectra of human serum albumin samples indicated that impurities are sometimes present which can be removed by charcoal at neutral pH, and acid-charcoal treatment is a much more rapid method of removing lipid impurities than other methods previously described.
Journal ArticleDOI
Solute perturbation of protein fluorescence. The quenching of the tryptophyl fluorescence of model compounds and of lysozyme by iodide ion.
TL;DR: The results of the model compound study provide evidence for a mechanism that follows the classical Stern-Volmer law (1919), predominantly involving collisional quenching, and illustrate the importance of local charge and solvent viscosity.