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Published on: April 6, 2017
Ponceau 4R induces aggregation in human serum albumin and morin acts as an anti-aggregating agent against dye induced
Maham Fatima1, Faisal Nabi2, Rizwan Hasan Khan2
1Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202002, U.P., India.
Abstract:
Aggregation of proteins occurs because of improper protein folding and is responsible for the development of multiple severe maladies such as Type II diabetes mellitus, Parkison's, Huntington's, and spongiform encephalopathy. In the current work, the interaction and aggregation of human serum albumin (HSA) in the presence of the food colorant Ponceau 4R at pH 2.0 was evaluated using multiple in-silico and multi-spectroscopic approaches. The UV-visible spectroscopy and steady state fluorescence spectroscopy confirmed the complex formation between Ponceau 4R and HSA. The binding of HSA to Ponceau 4R favored static mode of fluorescence quenching. The values of KSV and Kb were found to be 1.905 × 105 M-1 and 1.43 × 105 M-1 respectively. Ponceau 4R leads to modification of HSA microenvironment, as proven by three-dimensional fluorescence spectroscopy. Ponceau 4R in the concentration range (60-200 µM) triggered the aggregation of HSA at pH 2.0 as confirmed by turbidity and Rayleigh light scattering (RLS). The secondary structure alteration of human serum albumin (α-helical structure to cross-β conformation) induced by 140 µM Ponceau 4R was evaluated utilizing far-UV CD spectroscopy. This concentration of Ponceau 4R (140 µM) will now be further used in aggregation inhibition studies. The production of β-rich aggregates of HSA is further established by a red shift in the absorption maxima of the Congo red spectra. The scanning electron microscopy (SEM) results showed that HSA aggregates induced by Ponceau 4R were amorphous in nature. Molecular docking analysis showed that electrostatic interactions, hydrophobic interactions and hydrogen bonding were responsible for the Ponceau 4R-induced aggregation of HSA. Furthermore, morin further inhibits the Ponceau 4R-induced aggregation of HSA. The results from turbidity, RLS, and SEM analysis confirmed that aggregates of HSA induced by 140 µM Ponceau 4R became soluble when human serum albumin was pre-incubated with various amounts of morin (0-600 µM). Thus, we conclude that Ponceau 4R triggers the aggregation of human serum albumin, whereas morin is responsible for the inhibition of aggregation of protein.
Insights
Food dye Ponceau 4R induces human serum albumin (HSA) aggregation by altering its structure. Morin effectively inhibits this aggregation, offering potential therapeutic insights for protein misfolding diseases.
Area of Science:
- Biochemistry
- Molecular Biology
- Food Science
Background:
- Protein misfolding and aggregation are implicated in severe diseases like diabetes, Parkinson's, and Alzheimer's.
- Understanding the molecular mechanisms of protein aggregation is crucial for developing therapeutic strategies.
Purpose of the Study:
- To investigate the interaction between the food colorant Ponceau 4R and human serum albumin (HSA) at pH 2.0.
- To elucidate the role of Ponceau 4R in inducing HSA aggregation and explore morin's inhibitory effects.
Main Methods:
- Utilized UV-visible spectroscopy, fluorescence spectroscopy, and 3D fluorescence spectroscopy to study HSA-Ponceau 4R complex formation and microenvironment changes.
- Employed turbidity, Rayleigh light scattering (RLS), far-UV circular dichroism (CD) spectroscopy, Congo red assay, and scanning electron microscopy (SEM) to analyze HSA aggregation.
- Performed molecular docking to identify the interaction modes between Ponceau 4R and HSA.
Main Results:
- Ponceau 4R forms a complex with HSA, leading to static fluorescence quenching and modification of HSA's microenvironment.
- Ponceau 4R (60-200 µM) induces HSA aggregation at pH 2.0, causing structural changes from α-helical to β-rich conformations.
- Molecular docking revealed electrostatic, hydrophobic, and hydrogen bonding interactions driving aggregation; morin effectively inhibited Ponceau 4R-induced HSA aggregation.
Conclusions:
- Ponceau 4R acts as an inducer of human serum albumin aggregation.
- Morin demonstrates significant potential as an inhibitor of Ponceau 4R-induced protein aggregation.
- Findings provide insights into food additive-induced protein aggregation and potential mitigation strategies.
