Spectroscopic investigations to reveal the nature of interactions between the haem protein myoglobin and the dye rhodamine 6G

Abstract

In the present investigation, steady-state and time-resolved fluorescence with the combination of circular dichroism (CD) spectroscopic techniques were applied to study the interactions of the well-known dye rhodamine 6 G (R6G) with the haem protein human myoglobin (Mb). From the analysis of the results it appears that the static type of fluorescence quenching mechanism is primarily involved, due to ground-state interactions. Although considerable overlapping of fluorescence emission of the dye R6G with the absorption of Mb in the Q-band region exists, the possibility of occurrences of the excitational singlet-singlet non-radiative energy transfer process from R6G to Mb appears to be unlikely, according to time-resolved fluorescence measurements. From the determinations of the thermodynamic parameters, it was apparent that the combined effect of van der Waals' interactions and hydrogen bonding plays a vital role in Mb-R6G interactions. Induced circular dichroism (ICD) studies demonstrate the possibility of interactions between R6G and Mb. The binding constants, number of binding sites and thermodynamic parameters have been computed. From CD measurements it is apparent that the binding of the dye R6G with the haem protein Mb induces negligible conformational changes in the protein and Mb retains its secondary structure and helicity when it interacts with R6G. The present detailed studies on the interactions with Mb should be helpful in further advancement of medical diagnostics and biotechnology.

Fluorescence Modulation by Absorbent on Solid Surface: An Improved Approach for Designing Fluorescent Sensor

“…Fluorescence anisotropy (FA) results (Figure S7, Supporting Information) could explain the reason. The increase in FA values of R6G after addition of bovine serum means that the strong interaction between dye and bovine serum protein interferes with the spectroscopic properties of dye . In the meantime, absorbance of CP also decrease after addition of bovine serum because the reaction between probe molecule and Cys residue of bovine serum albumin (Figure S8, Supporting Information).…”

“…The increase in FA values of R6G after addition of bovine serum means that the strong interaction between dye and bovine serum protein interferes with the spectroscopic properties of dye. 38 In the meantime, absorbance of CP also decrease after addition of bovine serum because the reaction between probe molecule and Cys residue of bovine serum albumin (Figure S8, Supporting Information). As a consequence, the IFE efficiency and response performance of R6G/CP under serum condition would be discounted by the adverse effects of serum on both absorber and fluorophore (Figure S9, Supporting Information).…”

Targeting the heme proteins hemoglobin and myoglobin by janus green blue and study of the dye–protein association by spectroscopy and calorimetry

“…Recently, a number of studies on small molecules binding to Hb have been reported [5][6][7][8][9][10][11][12][13][14][15] while studies on the binding of small molecules to Mb are scarce. [16][17][18][19] Janus green B (JGB) (3-(diethylamino-7-(4-dimethyl amino phenyl azo)-5-phenylphenazinium chloride)) (Fig. 1) is a basic phenazinium dye having anti malarial potency 20 and known to behave as an accurate inhibitor for specic supravital staining of mitochondria.…”