화학공학소재연구정보센터
Journal of Physical Chemistry B, Vol.120, No.46, 11905-11911, 2016
Human Islet Amyloid Polypeptide Assembly: The Key Role of the 8-20 Fragment
The aggregation of human islet amyloid polypeptide (hIAPP) has been closely associated with the pathogeny of type 2 diabetes mellitus (T2DM) and destruction of pancreatic islet beta-cells. Several amyloidogenic domains within the hIAPP sequence capable of self-association have been identified. Among them is the 8-20 region of hIAPP, which has formed beta-sheet fibrils despite being contained within an alpha-helical region of full-length hIAPP. To further understand the propensity of this region for self-assembly, two peptide fragments were compared, one consisting of the residues 8-20 (WT8-20) and a mutant fragment with a Hisl8Pro substitution (H18P(8-20)). The conformational distribution and aggregation propensity of these peptides was determined using a combination of ion mobility mass spectrometry and atomic force microscopy. Our results reveal that the two peptide fragments have vastly differing assembly pathways. WT8-20 produces a wide range of oligomers up to decamer whereas the H18P(8-20) mutant produces only low order oligomers. This study confirms the propensity of the 8-20 region to aggregate from its native alpha-helical structure into amyloid beta-sheet oligomers and highlights the significance of the charged His18 in the aggregation process.