Influence of Ascorbic Acid on the Structure and Function of Alpha-2- macroglobulin: Investigations using Spectroscopic and Thermodynamic Techniques

Author(s): Syed Saqib Ali, Mohammad Khalid Zia, Tooba Siddiqui, Haseeb Ahsan, Fahim Halim Khan*.

Journal Name: Protein & Peptide Letters

Volume 27 , Issue 3 , 2020

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Graphical Abstract:


Background: Ascorbic acid is a classic dietary antioxidant which plays an important role in the body of human beings. It is commonly found in various foods as well as taken as dietary supplement.

Objective: The plasma ascorbic acid concentration may range from low, as in chronic or acute oxidative stress to high if delivered intravenously during cancer treatment. Sheep alpha-2- macroglobulin (α2M), a human α2M homologue is a large tetrameric glycoprotein of 630 kDa with antiproteinase activity, found in sheep’s blood.

Methods: In the present study, the interaction of ascorbic acid with alpha-2-macroglobulin was explored in the presence of visible light by utilizing various spectroscopic techniques and isothermal titration calorimetry (ITC).

Results: UV-vis and fluorescence spectroscopy suggests the formation of a complex between ascorbic acid and α2M apparent by increased absorbance and decreased fluorescence. Secondary structural changes in the α2M were investigated by CD and FT-IR spectroscopy. Our findings suggest the induction of subtle conformational changes in α2M induced by ascorbic acid. Thermodynamics signatures of ascorbic acid and α2M interaction indicate that the binding is an enthalpy-driven process.

Conclusion: It is possible that ascorbic acid binds and compromises antiproteinase activity of α2M by inducing changes in the secondary structure of the protein.

Keywords: alpha-2-macroglobulin, ascorbic acid, fourier transform infrared spectroscopy, circular dichroism, isothermal titration calorimetry.

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Article Details

Year: 2020
Page: [201 - 209]
Pages: 9
DOI: 10.2174/0929866526666191002113525
Price: $65

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