Study of caffeine binding to human serum albumin using optical spectroscopic methods

Abstract

The binding of caffeine to human serum albumin (HSA) under physiological conditions has been studied by the methods of fluorescence, UV-vis absorbance and circular dichroism (CD) spectroscopy. The mechanism of quenching of HSA fluorescence by caffeine was shown to involve a dynamic quenching procedure. The number of binding sites n and apparent binding constant K b were measured by the fluorescence quenching method and the thermodynamic parameters ΔH, ΔG, ΔS were calculated. The results indicate that the binding is mainly enthalpy-driven, with van der Waals interactions and hydrogen bonding playing major roles in the reaction. The distance r between donor (HSA) and acceptor (caffeine) was obtained according to the Förster theory of non-radiative energy transfer. Synchronous fluorescence, CD and three-dimensional fluorescence spectroscopy showed that the microenvironment and conformation of HSA were altered during the reaction.caffeine, human serum albumin, fluorescence quenching, circular dichroism (CD) spectroscopy, UV-vis spectroscopy.

Utility of a xanthene‐based dye for determination of nilotinib using two spectroscopic approaches. Applications to bulk powder, capsules, and spiked human plasma

“…[ 22 ] Stern–Volmer method can provide an explanation for either a static or dynamic type of quenching process. [ 26,27 ] Stern–Volmer plots (Figure 5c) were assembled by plotting F 0 / F versus [ Q ] using the following equation: where F 0 is the fluorescence intensity in the absence of NIL, F is the fluorescence intensity in the presence of NIL, [Q] is the NIL molar concentration, and K SV is Stern–Volmer constant.…”

Utility of a novel turn-off fluorescence probe for the determination of tranilast, an adjunctive drug for patients with severe COVID-19

“…4c shows an increase in K sv values from 8.8 × 10 3 to 17.2 × 10 3 L mol −1 with an increase in temperature from 303 to 323 K, indicating dynamic quenching. 31–33…”

“…29 Consequently, static and dynamic quenching processes can be explained using the Stern-Volmer method. 31,32 The ratio between the uorescence intensities in the absence (F 0 ) and presence (F) of the quencher was plotted against the molar concentration of the quencher [Q] to create a Stern-Volmer plot, as shown in Fig. 4c.…”

“…4c shows an increase in K sv values from 8.8 Â 10 3 to 17.2 Â 10 3 L mol À1 with an increase in temperature from 303 to 323 K, indicating dynamic quenching. [31][32][33] Additionally, the bimolecular quenching constant (K q ) could be calculated from the following equation: 33…”

Study of Interaction of Dextromethorphan Hydrobromide with Deoxyribonucleic Acid by Fluorescence Quenching

“…Binding constant and binding points: When small molecule bind independently to a set of equivalent sites on a macromolecule, the equilibrium between free and bound molecule is given by the following equation (Wu et al, 2009): Data analysis: All the data were analyzed by using the software Microsoft Excel (MS Excel. 2013).…”