Science / Technology - Colloquium
Wednesday, February 6, 2008
4:00 PM-5:00 PM
Olin Hall
107
Measuring the dynamical properties of unfolded chains in solution, and in particular of amyloid forming peptides, is of key importance to understand the first elementary steps in folding, misfolding and aggregation. Protein misfolding and aggregation is at the basis of a vast class of diseases (including Alzheimer's and type II Diabetes) called amyloid diseases, where aggregates of specific structure, called amyloid fibrils, are formed. In type II Diabetes a peptide called human islet amyloid polypeptide (hIAPP) forms amyloid fibrils inside the b-cells of the pancreas (where insulin is produced) contributing to b-cell death and consequent impairment of insulin production.
In order to understand aggregation it is critical to know what the constituents are. As an example I will present a study of IAPP, where we have directly compared an aggregating variant (hIAPP) to a non-aggregating variant (rIAPP), in their monomeric states. Before aggregating into highly ordered amyloid fibrils the hIAPP monomer is known to be unstructured. This poses the fundamental question of how to parameterize an unstructured chain. We do this by measuring the rates of intra-molecular end-to-end contact formation using tryptophan triplet quenching by cystine. We find a significant chain collapse in aqueous solvent for both peptides, and the appearance of kinetic traps that slow down chain dynamics. Interestingly rIAPP shows an increased chain stiffness with respect to hIAPP.
Cost: FREE
Sponsored by: WPI Physics Department, Dr. Stephan Koehler
Suggested Audiences: College
E-mail:
sak@wpi.edu
Phone: 508-831-5090
Last Modified: January 23, 2008 at 10:06 AM
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