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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DNA-induced conformational changes in bacteriophage 434 repressor.
TL;DR: The authors showed that both specific and non-specific DNA induce conformational changes in repressor that lead to formation of repressor dimers, suggesting that the alternative conformations persist even if the protein is not in direct contact with DNA, thus, DNA acts in a catalytic fashion to induce a steady-state amount of an alternative repressor conformation that has an enhanced affinity for its specific binding site.
Journal ArticleDOI
Correlation between activity and dynamics of the protein matrix of phosphorylase b
TL;DR: A model, suggesting the cross-correlation of activity and fluctuation, was consistent with the experimental findings and concluded that the quenching was mainly of dynamic character.
Journal ArticleDOI
Steady-state and picosecond time-resolved fluorescence studies on native and apo seed coat soybean peroxidase.
TL;DR: From fluorescence resonance energy transfer (FRET) calculations, the energy-transfer efficiency in SBP is found to be relatively higher as compared to HRP-C and is attributed mainly to the higher value of orientation factor, kappa(2) for SBP.
Journal ArticleDOI
Interactions of human serum albumin with meloxicam: characterization of binding site.
TL;DR: The strong quenching of the fluorescence clearly indicated that the binding of the drug to HSA changed the microenvironment of tryptophan residue and the tertiary structure of HSA, and marked reductions in the affinity of albumin for bilirubin upon meloxicam binding were reported.
Journal ArticleDOI
Tailored xerogel-based sensor arrays and artificial neural networks yield improved O2 detection accuracy and precision.
Ying Tang,Zunyu Tao,Rachel M. Bukowski,Elizabeth C. Tehan,S.S. Karri,Albert H. Titus,Frank V. Bright +6 more
TL;DR: This research trained an artificial neural network to "learn" to identify the optical outputs from these xerogel-based sensor arrays and explored the response characteristics of these types of sensor elements after they had been contacted with rat plasma/blood.
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.