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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Oleuropein aglycone and hydroxytyrosol interfere differently with toxic Aβ1-42 aggregation
TL;DR: The data demonstrate that, by stabilizing oligomers and fibrils, both polyphenols reduce their seeding activity and aggregate/membrane interaction on human neuroblastoma SH-SY5Y cells, and offer the possibility to validate and to optimize their use for possible AD prevention and therapy.
Journal ArticleDOI
Characterization of the Metal Ion Binding Properties of the Hepatitis C Virus RNA Polymerase
TL;DR: It is proposed that the ion-induced conformational change is a prerequisite for catalytic activity by both correctly positioning the side chains of the residues located in the active site of the enzyme and also contributing to the stabilization of the intermediate transition state.
Journal ArticleDOI
Enhancement of thermal stability of chondroitinase ABC I by site-directed mutagenesis: an insight from Ramachandran plot.
TL;DR: Results indicated that Q140G and Q140A mutants were able to improve both activity and thermal stability of the enzyme while Q140N variant reduced the enzyme activity and destabilized it.
Journal ArticleDOI
Fluorescence analysis of the Escherichia coli transcription regulator H-NS reveals two distinguishable complexes dependent on binding to specific or nonspecific DNA sites.
Detlev Tippner,Rolf Wagner +1 more
TL;DR: A structural investigation of the transcription factor H-NS and its DNA interaction is reported, taking advantage of the intrinsic fluorescence of Trp-108 to overcome the apparent lack of any other structural details.
Journal ArticleDOI
β2-Microglobulin amyloid fibril-induced membrane disruption is enhanced by endosomal lipids and acidic pH.
Sophia C. Goodchild,Tania Sheynis,Rebecca F. Thompson,Kevin W. Tipping,Wei-Feng Xue,Neil A. Ranson,Paul A. Beales,Eric W. Hewitt,Sheena E. Radford +8 more
TL;DR: It is shown that β2m fibril-induced membrane disruption is modulated by anionic lipid composition and is enhanced by acidic pH, and the interaction between β2M fibrils and membranes of endosomal origin may play a role in the molecular mechanism ofβ2m amyloid-associated osteoarticular tissue destruction in DRA.
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.