Study of the interaction between N-confused porphyrin and bovine serum albumin by fluorescence spectroscopy

Thermodynamic Aspects of Binding Proteins with Porphyrins. Spectral and Thermochemical Approaches

“…The obtained value of the association constant of Porphyrin 1 with BSA calculated according to equation (4) is consistent with the data reported in, [23] despite the fact that the studies were carried out at different pH values. Thermodynamic parameters of the investigated processes were determined from the temperature dependence of the association constants (Table 1) by the Van't Hoff equation (Table 2).…”

“…From the standpoint of physical chemistry this constant should be regarded as an empirical constant adsorption or the association constant. However, in a series of studies, [22][23][24] the constant calculated from the isotherms of binding is equated with the thermodynamic stability constant of albumin complexes with ligands. It is invalid viewpoint.…”

“…In addition, it is difficult to determine the concentration of free porphyrin, because the absorption spectra of free porphyrin and in the complex with the protein significantly overlap. Probably, last factor is the cause of the scatter of the data presented in [22,23] and Table 1.…”

Characterization of diadzein–hemoglobin binding using optical spectroscopy and molecular dynamics simulations

“…The apparent binding constant ‘ K ’ and the number of binding site(s) ‘ n ’ were estimated from fluorescence titration studies, using the plot of log(F 0 -F)/F vs. log[Q] [31] (Figure 3A) which is based on equation (2) [31, 32] $$\text{log}\frac{F_0-F}{F}=\text{log }K+n\text{ log}[Q]$$ where F 0 and F are the fluorescence intensity of HbA in absence and presence of isoflavonoid (DZN) respectively, Q is the DZN concentration, n is the number of binding sites and K is the binding constant. Table 1 shows the Stern-Volmer quenching ( K SV ) and binding constants ‘ K ’ for the binding of DZN to HbA within the studied concentration range of the flavonoids.…”

Comparison study on the interaction mechanisms of B. amyloliquefaciens amylase with PEG-400 and TEPA and the properties of enzyme

“…That indicates the binding was driven by van der waals force and hydrogen bonding [58]. The negative value of DS for the interaction implies the reduced freedom and increased conformational stability of BAA when PEG approach to BAA [59]. In the case of TEPA addition (Table 3), the small value of DH for the binding of TEPA to BAA denotes the binding primarily involved ionic interaction [58,60].…”