James S Nowick

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Molecules that fold to mimic protein secondary structures have emerged as important targets of bioorganic chemistry. Recently, a variety of compounds that mimic helices, turns, and sheets have been developed, with notable advances in the design of beta-peptides that mimic each of these structures. These compounds hold promise as a step toward synthetic(More)
Although aberrant protein aggregation has been conclusively linked to dozens of devastating amyloid diseases, scientists remain puzzled about the molecular features that render amyloid fibrils or small oligomers toxic. Here, we report a previously unobserved type of amyloid fibril that tests as cytotoxic: one in which the strands of the contributing(More)
The amyloid protein aggregation associated with diseases such as Alzheimer's, Parkinson's and type II diabetes (among many others) features a bewildering variety of β-sheet-rich structures in transition from native proteins to ordered oligomers and fibres. The variation in the amino-acid sequences of the β-structures presents a challenge to developing a(More)
Protein amyloid oligomers have been strongly linked to amyloid diseases and can be intermediates to amyloid fibers. β-Sheets have been identified in amyloid oligomers. However, because of their transient and highly polymorphic properties, the details of their self-association remain elusive. Here we explore oligomer structure using a model system:(More)
BACKGROUND In vitro selected ribozymes with nucleotide synthase, peptide and carbon-carbon bond forming activity provide insight into possible scenarios on how chemical transformations may have been catalyzed before protein enzymes had evolved. Metabolic pathways based on ribozymes may have existed at an early stage of evolution. RESULTS We have isolated(More)
Recent reports by Galeazzi and co-workers demonstrated the susceptibility of Abeta(1-42) to undergo dityrosine formation via peroxidase-catalyzed tyrosine cross-linking. We have formed dityrosine cross-links in Abeta(1-40) using these enzymatic conditions as well as a copper-H(2)O(2) method. The efficiency of dityrosine cross-link formation is strongly(More)
Amyloid formation is implicated in more than 20 human diseases, yet the mechanism by which fibrils form is not well understood. We use 2D infrared spectroscopy and isotope labeling to monitor the kinetics of fibril formation by human islet amyloid polypeptide (hIAPP or amylin) that is associated with type 2 diabetes. We find that an oligomeric intermediate(More)
Amyloid diseases such as Alzheimer's disease, Parkinson's disease, and type II diabetes share common features of toxic soluble protein oligomers. There are no structures at atomic resolution of oligomers formed by full-length amyloidogenic peptides and proteins, and only a few structures of oligomers formed by peptide fragments. The paucity of structural(More)
Beta-sheets consist of extended polypeptide strands (beta-strands) connected by a network of hydrogen bonds and occur widely in proteins. Although the importance of beta-sheets in the folded structures of proteins has long been recognized, there is a growing recognition of the importance of intermolecular interactions among beta-sheets. Intermolecular(More)
This paper seeks to understand how a macrocyclic β-sheet peptide inhibits the aggregation of the tau-protein-derived peptide Ac-VQIVYK-NH2 (AcPHF6). Previous studies established that macrocyclic β-sheet peptide 1 inhibits AcPHF6 aggregation, while the sequence isomer in which the lysine and leucine residues at positions R6 and R7 are swapped has little(More)