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Low levels of asparagine deamidation can have a dramatic effect on aggregation of amyloidogenic peptides: Implications for the study of amyloid formation
Author(s) -
Nilsson Melanie R.,
Driscoll Miles,
Raleigh Daniel P.
Publication year - 2002
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.48702
Subject(s) - deamidation , amylin , peptide , chemistry , amyloid (mycology) , asparagine , biochemistry , peptide sequence , protein secondary structure , residue (chemistry) , protein aggregation , biophysics , amino acid , islet , insulin , enzyme , biology , endocrinology , inorganic chemistry , gene
The polypeptide hormone amylin forms amyloid deposits in Type 2 diabetes mellitus and a 10‐residue fragment of amylin (amylin 20–29 ) is commonly used as a model system to study this process. Studies of amylin 20–29 and several variant peptides revealed that low levels of deamidation can have a significant effect on the secondary structure and aggregation behavior of these molecules. Results obtained with a variant of amylin 20–29 , which has the primary sequence SNNFPAILSS, are highlighted. This peptide is particularly interesting from a technical standpoint. In the absence of impurities the peptide does not spontaneously aggregate and is not amyloidogenic. This peptide can spontaneously deamidate, and the presence of less than 5% of deamidation impurities leads to the formation of aggregates that have the hallmarks of amyloid. In addition, small amounts of deamidated material can induce amyloid formation by the purified peptide. These results have fundamental implications for the definition of an amyloidogenic sequence and for the standards of purity of peptides and proteins used for studies of amyloid formation.