Food Additive Hexametaphosphate Promotes Amyloid Formation in Human Serum Albumin: A Molecular Insight.

Area of Science:

• Biochemistry
• Protein Chemistry
• Materials Science

Background:

• Human serum albumin (HSA) is a crucial protein in blood plasma.
• Protein aggregation is linked to various diseases.
• Understanding protein behavior under different conditions is vital.

Purpose of the Study:

• To investigate the aggregation of human serum albumin (HSA) at different pH values when exposed to hexametaphosphate (HMP).
• To determine the structural changes and fibril formation of HSA in response to HMP.
• To elucidate the role of electrostatic interactions in HSA aggregation.

Main Methods:

• UV-Vis turbidity measurements
• Intrinsic fluorescence spectroscopy
• Far-UV circular dichroism (CD) spectroscopy
• Thioflavin T (ThT) fluorescence assays
• Rayleigh light scattering (RLS)
• Transmission electron microscopy (TEM)

Main Results:

• Cationic HSA (pH 2.0) aggregated with HMP in a concentration-dependent manner, forming amyloid-like fibrils.
• Anionic HSA (pH 8.0) remained soluble and structurally intact in the presence of HMP.
• HMP induced conformational changes in cationic HSA, leading to alpha-helical structure loss and beta-sheet formation.
• Aggregation of cationic HSA was rapid and occurred without a lag phase.

Conclusions:

• HSA aggregation is significantly influenced by pH and electrostatic interactions.
• Cationic HSA exhibits amyloidogenic potential upon interaction with polyanionic compounds like HMP.
• Anionic HSA is resistant to HMP-induced aggregation and structural changes.