Allura red rapidly induces amyloid-like fibril formation in hen egg white lysozyme at physiological pH

Nasser Abdulatif Al-Shabib; Javed Masood Khan; Ajamaluddin Malik; Priyankar Sen; Sriroopreddy Ramireddy; Sudandiradoss Chinnappan; Salman Freeh Alamery; Fohad Mabood Husain; Aqeel Ahmad; Hani Choudhry; Mohmmad Imran Khan; Sayed Ali Shahzad

doi:10.1016/j.ijbiomac.2019.01.049

Allura red rapidly induces amyloid-like fibril formation in hen egg white lysozyme at physiological pH

Int J Biol Macromol. 2019 Apr 15:127:297-305. doi: 10.1016/j.ijbiomac.2019.01.049. Epub 2019 Jan 14.

Affiliations

¹ Department of Food Science and Nutrition, Faculty of Food and Agricultural Sciences, King Saud University, Riyadh, Saudi Arabia. Electronic address: [email protected].
² Department of Food Science and Nutrition, Faculty of Food and Agricultural Sciences, King Saud University, Riyadh, Saudi Arabia. Electronic address: [email protected].
³ Protein Research Chair, Department of Biochemistry, College of Science, King Saud University, Riyadh, Saudi Arabia.
⁴ Centre for Bioseparation Technology, Vellore Institute of Technology (VIT) University, Vellore, India.
⁵ Department of Biotechnology, School of Biosciences and Technology, Vellore Institute of Technology, Vellore, India.
⁶ Center of Excellence in Biotechnology Research, Department of Biochemistry, College of Science, King Saud University, Saudi Arabia.
⁷ Department of Food Science and Nutrition, Faculty of Food and Agricultural Sciences, King Saud University, Riyadh, Saudi Arabia.
⁸ Department of Medical Biochemistry, College of Medicine, Shaqra University, Shaqra, Saudi Arabia.
⁹ Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.

PMID: 30654033
DOI: 10.1016/j.ijbiomac.2019.01.049

Abstract

Allura red (AR) is an artificial azo dye mostly used in food industries and has potential health risks. We examined the role of AR in amyloidogenesis using hen egg white lysozyme (HEWL) at pH 7.0. The amyloidogenic induction properties of AR in HEWL were identified by circular dichroism (CD), turbidity, intrinsic fluorescence, light scattering, transmission electron microscopy (TEM), and molecular dynamic simulation studies. Turbidity and light scattering measurements showed that HEWL becomes aggregated in the presence of 0.03-15.0 mM of AR at pH 7.0 but not at very low AR concentrations (0.01-0.28 mM). However, AR-induced aggregation is a kinetically rapid process, with no observable lag phase and saturation within 6 s. The kinetics results suggested that the HEWL aggregation induced by AR is very rapid. The CD results demonstrated that the total β-sheet content of HEWL was increased in the AR treated samples. The TEM results are established that AR-induced aggregates had amyloid-like structures. Molecular dynamics simulations analysis showed that the bound AR-HEWL structures were highly favored compared to unbound structures. The mechanism of AR-induced amyloid fibril formation may involve electrostatic, hydrogen bonding, and hydrophobic interactions.

Keywords: Allura red; Amyloid fibril; Food additive dye; Lysozyme; Protein aggregation and pH.

MeSH terms

Amyloid / chemistry*
Animals
Azo Compounds / chemistry*
Chickens
Hydrogen-Ion Concentration
Muramidase / chemistry*
Protein Aggregates*
Protein Domains
Protein Structure, Quaternary

Substances

Amyloid
Azo Compounds
Protein Aggregates
Allura Red AC Dye
hen egg lysozyme
Muramidase