Disulfide bridges remain intact while native insulin converts into amyloid fibrils.
Amyloid fibrils are β-sheet-rich protein aggregates commonly found in the organs and tissues of patients with various amyloid-associated diseases. Understanding the structural organization of amyloid fibrils can be beneficial for the search of drugs to successfully treat diseases associated with protein misfolding. The structure of insulin fibrils was characterized by deep ultraviolet resonance Raman (DUVRR) and Nuclear Magnetic Resonance (NMR) spectroscopy combined with hydrogen-deuterium exchange. The compositions of the fibril core and unordered parts were determined at single amino acid residue resolution. All three disulfide bonds of native insulin remained intact during the aggregation process, withstanding scrambling. Three out of four tyrosine residues were packed into the fibril core, and another aromatic amino acid, phenylalanine, was located in the unordered parts of insulin fibrils. In addition, using all-atom MD simulations, the disulfide bonds were confirmed to remain intact in the insulin dimer, which mimics the fibrillar form of insulin.
Department of Chemistry, University at Albany, State University of New York, Albany, New York, United States of America.
Dmitry
D
Kurouski
Jacqueline
J
Washington
Mehmet
M
Ozbil
Rajeev
R
Prabhakar
Alexander
A
Shekhtman
Igor K
IK
Lednev
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000378:metabolism; D000682:Amyloid / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D041961:Deuterium Exchange Measurement; D004220:Disulfides / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000737:chemistry* / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D012996:Solutions
D000596:Amino Acids; D000682:Amyloid; D004220:Disulfides; D007328:Insulin; D012996:Solutions