Fluorescence spectroscopy extrinsic

Fluorescence spectroscopy is also particularly well-suited to clarify many aspects of polymer/surfactant interactions on a molecular scale. The technique provides information on the mean aggregation numbers of the complexes formed and measures of the polarity and internal fluidity of these structures. Such interactions may be monitored by fluorescence not only with extrinsic probes or labelled polymers, but also by using fluorescent surfactants. Schild and Tirrell [154] have reported the use of sodium 2-(V-dodecylamino) naphthalene-6-sulfonate (SDN6S) to study the interactions between ionic surfactants and poly(V-isopropylacrylamide). 

Fluorescence spectroscopy S Conformational change with ligand binding induces change in fluorescence properties of intrinsic or extrinsic fluorophore... 

Comprehensive reviews (Kl, Ul) of the active sites of cholinesterase both postulated the presence not only of an esteratic site for butyrylcholinesterase but also of an anionic site. Additionally, in the region of the anionic site, there are two hydrophobic areas, one directly surrounding the anionic group and the second located at some distance from it (Kl). The presence of hydrophobic areas has been established (B32, C3, H29, H45, MIO) by the use of fluorescent probes with spectral responses which reflect the environment of the probe. Such probes can be used to monitor changes in the conformations of enzymes and can be designed to be active-site-directed, competitive inhibitors (H30). Aspects of the spectroscopy of intrinsic and extrinsic fluorescent probes have been reported (C3). 

Aladan substitution of internal core amino-acid residues provides an approach to characterise the physical characteristics of protein cores. Steady-state fluorescence alone can provide initial insight to the immediate environment of Aladan in the protein core. However, time-resolved fluorescence spectroscopy can be used to understand variations in protein core composition and structure as a function of time through the characterisation of Aladan fluorescence intensity and /max changes that are caused by small fluctuations in the relative permittivity, e, of the protein interior with time (fs-ps timescale). Such spectroscopy is possible since fluorescence lifetimes, Tr, are typically in the ns range (see Section 4.5). Also, time-resolved fluorescence spectroscopy can be performed with non-covalently linked extrinsic fluorophores such as ethidium bromide (EtBr). This fluorophore intercalates between the bases of DNA or RNA double helix and in so doing acquires a substantial increase in (j) and hence fluorescence intensity at /max (595 nm). Should there be a disruption or collapse in double-helical structure, then intercalation fails and fluorescent intensity drops... 

In this second edition of Principles of Fluorescence Spectroscopy, I have attempted to maintain the emj asis on basics, while updating the examples to include more recent results from the literature. Iliere is a new chapter providing an overview of extrinsic fluoroj ores. The discussion of time-resolved measurements has been ex-... 

As nonconjugated and nonaromatic polymers are nonfluorescent, studies of their phase behavior using fluorescence spectroscopy require the use of extrinsic fluorescent labels [38-40]. These can be either selectively dissolved into the polymer phases [41] or, most commonly, attached covalently to the polymer chains [42-47]. A criticism that is often made of using extrinsic fluorescent probes is the possible local perturbation induced by the probe itself on the nanoenvironment to be probed. In order to minimize such perturbation, the size and shape of the probe should be chosen so as to cause the minimum possible perturbation on the probed region. 

Chakraborty, R. Berglund, K. A. Steady state fluorescence spectroscopy of pyranine as a trace extrinsic probe to study structure in aqueous sugar solutions. J. Cryst. Growth 1992,125, 81-96. 

Femtosecond spectroscopy has an ideal temporal resolution for the study of ultrafast water motions from femtosecond to picosecond time scales [33-36]. Femtosecond solvation dynamics is sensitive to both time and length scales and can be a good probe for protein hydration dynamics [16, 37-50]. Recent femtosecond studies by an extrinsic labeling of a protein with a dye molecule showed certain ultrafast water motions [37-42]. This kind of labeling usually relies on hydrophobic interactions, and the probe is typically located in the hydrophobic crevice. The resulting dynamics mostly reflects bound water behavior. The recent success of incorporating a synthetic fluorescent amino acid into the protein showed another way to probe protein electrostatic interactions [43, 48]. 

The relaxation time did not depend on the parameters used to follow the kinetics, but only on the final temperature. It was found to be identical using optical rotation, absorption spectroscopy at different wavelengths, and fluorescence. Furthermore, when an extrinsic probe was used (fluorescence or absorption variations of the anthranyloyl group in anthranyloyl chymotrypsin) the same relation time was observed. 

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