Nicking and fragmentation are responsible for α‐lactalbumin amyloid fibril formation at acidic pH and elevated temperature

Amyloid fibrils are ordered aggregates that may be formed from disordered, partially unfolded, and fragments of proteins and peptides. There are several diseases, which are due to the formation and deposition of insoluble β‐sheet protein aggregates in various tissue, collectively known as amyloidosi...

Full description

Saved in:

Bibliographic Details
Published in:	Protein science 2021-09, Vol.30 (9), p.1919-1934
Main Authors:	Rahamtullah, Mishra, Rajesh
Format:	Article
Language:	eng
Subjects:	Aggregates aggregation Amino Acid Sequence Amyloid Amyloid - chemistry Amyloid - metabolism Amyloidogenic Proteins - chemistry Amyloidogenic Proteins - metabolism Amyloidosis Animals Atomic force microscopy Benzothiazoles - chemistry Cattle Circular dichroism Dichroism Fibrillation Fibrils Flight operations Fluorescence Fragmentation Fragments Full‐Length Paper Full‐Length Papers High temperature Hot Temperature Hydrogen-Ion Concentration Ionization Lactalbumin Lactalbumin - chemistry Lactalbumin - metabolism Mass spectrometry Mass spectroscopy Microscopy, Atomic Force Models, Chemical Nucleation Peptides pH effects Protein Conformation, alpha-Helical Protein Conformation, beta-Strand Proteins Proteolysis Raman spectroscopy Spectrometry, Fluorescence α‐lactalbumin
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	Amyloid fibrils are ordered aggregates that may be formed from disordered, partially unfolded, and fragments of proteins and peptides. There are several diseases, which are due to the formation and deposition of insoluble β‐sheet protein aggregates in various tissue, collectively known as amyloidosis. Here, we have used bovine α‐lactalbumin as a model protein to understand the mechanism of amyloid fibril formation at pH 1.6 and 65°C under non‐reducing conditions. Amyloid fibril formation is confirmed by Thioflavin T fluorescence and atomic force microscopy (AFM). Our finding demonstrates that hydrolysis of peptide bonds occurs under these conditions, which results in nicking and fragmentation. The nicking and fragmentation have been confirmed on non‐reducing and reducing gel. We have identified the fragments by matrix‐assisted laser desorption ionization‐time of flight (MALDI‐TOF) mass spectrometry. The fragmentation may initiate nucleation as it coincides with AFM images. Conformational changes associated with monomer resulting in fibrillation are shown by circular dichroism and Raman spectroscopy. The current study highlights the importance of nicking and fragmentation in amyloid fibril formation, which may help understand the role of acidic pH and proteolysis under in vivo conditions in the initiation of amyloid fibril formation.
ISSN:	0961-8368 1469-896X