10.1021/ja406831n.s001
Lydia
M. Young
Lydia
M.
Young
Ping Cao
Ping
Cao
Daniel P. Raleigh
Daniel P.
Raleigh
Alison E. Ashcroft
Alison E.
Ashcroft
Sheena E. Radford
Sheena E.
Radford
Ion Mobility
Spectrometry–Mass Spectrometry
Defines the Oligomeric Intermediates in Amylin Amyloid Formation and
the Mode of Action of Inhibitors
American Chemical Society
2015
Human amylin
CCS
inhibition
type II diabetes mellitus
mode
fibril assembly
silibinin bind
Amylin Amyloid Formation
fibrillar deposits
Spectrometry
amyloid formation
amyloid propensity
rat amylin
amyloid deposits
rIAPP
Oligomeric Intermediates
cause disease
EGCG
pancreatic islets
polyphenolic compounds epigallocatechin gallate
oligomer formation
hIAPP monomers
molecule
islet transplants
2015-12-17 00:14:33
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Ion_Mobility_Spectrometry_Mass_Spectrometry_Defines_the_Oligomeric_Intermediates_in_Amylin_Amyloid_Formation_and_the_Mode_of_Action_of_Inhibitors/2027664
The molecular mechanisms by which
different proteins assemble into
highly ordered fibrillar deposits and cause disease remain topics
of debate. Human amylin (also known as islet amyloid polypeptide/hIAPP)
is found in vivo as amyloid deposits in the pancreatic islets of sufferers
of type II diabetes mellitus, and its self-aggregation is thought
to be a pathogenic factor in disease and to contribute to the failure
of islet transplants. Here, electrospray ionization-ion mobility spectrometry-mass
spectrometry (ESI-IMS-MS) has been used to monitor oligomer formation
from IAPP. The detection, identification and characterization of oligomers
from both human and rat amylin (rIAPP) are described. Oligomers up
to and including hexamers have been detected for both peptides. From
ESI-IMS-MS derived collision cross sections (CCS), these species are
shown to be elongated in conformation. Collision-induced dissociation
(CID-MS/MS) revealed differences in the gas-phase stability of the
oligomers formed from hIAPP and rIAPP, which may contribute to their
differences in amyloid propensity. Using ESI-IMS-MS, the mode of inhibition
of amyloid formation from hIAPP using small molecules or co-incubation
with rIAPP was also investigated. We show that the polyphenolic compounds
epigallocatechin gallate (EGCG) and silibinin bind to specific conformers
within a dynamic ensemble of hIAPP monomers, altering the progress
of oligomerization and fibril assembly. Hetero-oligomer formation
also occurs with rIAPP but leads only to inefficient inhibition. The
results indicate that although different small molecules can be effective
inhibitors of hIAPP self-assembly, their modes of action are distinct
and can be distinguished using ESI-IMS-MS.