Binding Of Methyl Orange Research Articles

Binding of methyl orange and its homologs by polycations containing apolar pendant groups

AbstractThe binding of methyl orange, ethyl orange, and propyl orange by polycations involving various apolar pendant groups such as methyl, ethyl, benzyl, or dodecylbenzyl groups has been examined quantitatively by an equilibrium dialysis method at 5, 15, 25, and 35°C. The first binding constants and the thermodynamic parameters in the course of the binding have been calculated. The favorable free energy of the binding is accompanied by an entropy gain and an exothermic enthalpy change. The shorter the alkyl chain of the dyes or the polymers, the more negative is the enthalpy change and hence the smaller is the entropy change. Furthermore, an increase in binding affinity can be created in the polycation upon introduction of hydrophobic groups. In particular, the binding ability of the polycation containing a dodecylbenzyl group for methyl orange is almost 300‐fold that of bovine serum albumin. Therefore it is clear that hydrophobic interactions, as well as electrostatic ones, are involved in the binding.

Raman spectroscopic studies of ligand-protein interactions: The binding of methyl orange by bovine serum albumin

Laser Raman spectroscopy has been shown to provide a new approach for studying small molecule-protein interactions by vibrational spectroscopy. An important feature is that ordinary water solutions at pH values near 7 and low ligand concentrations (∼10 −5 molar) can be employed. Its use depends on ligands which yield intensity enhanced Raman spectra and is illustrated in a study of the interaction of methyl orange with bovine serum albumin.

The interaction of methyl orange and other azo-dyes with polyelectrolytes and with colloidal electrolytes in dilute aqueous solution

A detailed uv spectral investigation of the interaction of methyl orange (and other similar anionic azo-dyes) with four different synthetic cationic polyelectrolytes, with colloidal electrolytes, as well as with two proteins in dilute aqueous solutions, has been carried out. Under appropriate conditions, binding of methyl orange, ethyl orange, and butyl orange to poly( l-ornithine, poly- l-lysine), poly ( N-methylvinyl pyridinium chloride), and trimethyldodecylammonium chloride, gives rise to marked changes in the spectrum of each of the three dyes (but not of other dyes examined). These spectral changes are quite different from those which result from the binding of the azo-dyes on to the strongly ionized poly(vinylbenzyltrimethyl ammonium chloride) chains. The effects observed with the four synthetic polyelectrolytes mentioned above and with the colloidal electrolytes, are postulated to be connected with a conformational change of bound dye molecules. Interaction of methyl orange with bovine serum albumin and with lysozyme would mainly result in a partial solubilization of the dye in the hydrophobic regions of the proteins.

Nature of urea effect on anion binding by macromolecules

The binding of methyl orange by bovine serum albumin is suppressed by urea. However, the inhibition is largely reversible if urea is removed either by dialysis (fast or gradient) or by dilution. Binding by a synthetic polymer, polyvinylpyrrolidone, which is unordered and swollen in water, is also suppressed by urea. These observations indicate that urea effects are mediated largely through its action on the solvent.

Physicochemical studies on the binding of chemicals with proteins. VI. Spectrophotometric investigations of the binding of methyl orange with lens proteins

Binding of Methyl Orange with α- and β-crystallins, the main proteins of lens cortex, was examined spectrophotometrically, in the range of pH 1.7∼8.0. Further, this binding at pH 3.6 was studied by the use of dialysis equilibrium method. As a result, the following points were clarified. 1) The binding of Methyl Orange with α- and β-crystallins in the range of pH 1.7∼8.0 occurs between the sulfone group in Methyl Orange and positively charged amino acid residue in the proteins. No difference was observed in the binding mechanism between the two proteins. 2) The number of binding sites of with Methyl Orange with the two proteins at pH 3.6 is smaller than that in the higher pH range. This fact is considered to be due to changes in the structure of the proteins at pH 3.6. 3) The binding of Methyl Orange with α-crystallin becomes the maximum at around pH 3.6, and that with β-crystalline is at around pH 3.2. This fact is considered to be due to the acid-type structure of Methyl Orange in the acid region, resulting in static repulsion of the positively charged molecule, and decoiling of the protein structure in the acid region.

Physicochemical studies on the binding of chemicals with proteins. 3. The binding of methyl orange with lens proteins

The binding of methyl orange with bovine lens protein, α-crystallin and β-crystallin, was studied in various pH values by equilibrium dialysis method in 0.1 M phosphate buffer of pH 4.7∼8.9. At equilibrium, the relationship between the amount of bound methyl orange and the concentration of methyl orange followed the Langmuir-type equation for each protein. The maximum possible number of methyl orange bound to each protein remained constant independent of the pH values examined and the number with α-crystallin was 10-4 (mole methyl orange/g. α-crystallin) and that with β-crystallin was 10-5. Binding constant (k) with each protein decreased markedly with increasing pH. The binding affinity (Δμ) of methyl orange with each protein was calculated, variation of Δμ with pH values was examined, and the effect of protein charge at the binding was discussed. It was concluded that in the binding of methyl orange with these proteins, the electrostatic force was the most important factor and that the binding with α-crystallin was greatly affected by electrostatic force than that with β-crystallin.

Binding of ions by myosin. I. Note on the binding of methyl orange by myosin

Binding of ions by myosin. I. Note on the binding of methyl orange by myosin