Computational Catalysis and Materials Lab

Abstract: An amyloid protein belongs to a group of intrinsically disordered proteins (IDPs). Self-assembly of IDPs imparts toxic biological effects depending on the size in over 20 neurodegenerative diseases. Unfortunately, our understanding of amyloid polypeptides, as related to biomedical implications, is limited by their self-assembling nature. On the other hand, due to high structural flexibility, occasionally coupled with functional roles, Nature often uses IDPs as structure-switching biosensors for rapid and specific signaling processes. Thus, IDPs may serve as a new source of proteins that can readily be engineered into molecular sensors with unique sensing behaviors. In this talk, I will first present our study on the creation of a dual peptide system, where a pair of engineered -amyloid (A) variants, KLVFWAK and ELVFWAE, are not self-assembled but hetero-assembled in the presence of their assembly partners. We provide evidence that the resulting hetero-assemblies share molecular, structural and morphological similarities with typical amyloid self-assemblies formed by a single polypeptide (e.g., A). We anticipate that our dual peptide system may readily be adapted for precise control of amyloid assembly, for the study of size-dependent neurotoxicity. I will also describe our engineering efforts to create structurally flexible amyloid protein variants. These engineered proteins rapidly generate distinct fluorescence responses to the three major amyloid conformers (monomers, oligomers, and fibrils), as molecular sensors to profile aggregation states critical for neuropathology.

Unlike IDPs, globular proteins fold into compact structures, responsible for various biological functions. Interestingly, globular proteins also form amyloid fibrils under partially denaturing conditions, demonstrating that amyloid aggregation is a generic property of proteins. In the second half of my talk, I will present our recent study, where a globular protein, Bacillus circulans xylanase (BCX), aggregates into amyloid fibrils under native conditions. Interestingly, addition of KLVFWAK or ELVFWAE modulated the BCX amyloid aggregation. This study also provides insight into a correlation between kinetic stability and amyloid aggregation of BCX, and supports a view that IDP-derived peptide fragments can modulate amyloid aggregation of globular proteins. Lastly, I will discuss industrial implications of amyloid aggregation by globular proteins under non-denaturing conditions.

Overall, my talk will present new engineering opportunities with IDPs and illustrate overlooked molecular features shared between IDPs and globular proteins.

Speaker bio: Jin Ryoun Kim is an associate professor in the Department of Chemical and Biomolecular Engineering at New York University (NYU). Prior to his career at NYU, he earned his BS and MS degrees at Seoul National University and his PhD degree at the University of Wisconsin-Madison majoring in chemical engineering, follo

Abstract: An amyloid protein belongs to a group of intrinsically disordered proteins (IDPs). Self-assembly of IDPs imparts toxic biological effects depending on the size in over 20 neurodegenerative diseases. Unfortunately, our understanding of amyloid polypeptides, as related to biomedical implications, is limited by their self-assembling nature. On the other hand, due to high structural flexibility, occasionally coupled with functional roles, Nature often uses IDPs as structure-switching biosensors for rapid and specific signaling processes. Thus, IDPs may serve as a new source of proteins that can readily be engineered into molecular sensors with unique sensing behaviors. In this talk, I will first present our study on the creation of a dual peptide system, where a pair of engineered -amyloid (A) variants, KLVFWAK and ELVFWAE, are not self-assembled but hetero-assembled in the presence of their assembly partners. We provide evidence that the resulting hetero-assemblies share molecular, structural and morphological similarities with typical amyloid self-assemblies formed by a single polypeptide (e.g., A). We anticipate that our dual peptide system may readily be adapted for precise control of amyloid assembly, for the study of size-dependent neurotoxicity. I will also describe our engineering efforts to create structurally flexible amyloid protein variants. These engineered proteins rapidly generate distinct fluorescence responses to the three major amyloid conformers (monomers, oligomers, and fibrils), as molecular sensors to profile aggregation states critical for neuropathology.

Unlike IDPs, globular proteins fold into compact structures, responsible for various biological functions. Interestingly, globular proteins also form amyloid fibrils under partially denaturing conditions, demonstrating that amyloid aggregation is a generic property of proteins. In the second half of my talk, I will present our recent study, where a globular protein, Bacillus circulans xylanase (BCX), aggregates into amyloid fibrils under native conditions. Interestingly, addition of KLVFWAK or ELVFWAE modulated the BCX amyloid aggregation. This study also provides insight into a correlation between kinetic stability and amyloid aggregation of BCX, and supports a view that IDP-derived peptide fragments can modulate amyloid aggregation of globular proteins. Lastly, I will discuss industrial implications of amyloid aggregation by globular proteins under non-denaturing conditions.

Overall, my talk will present new engineering opportunities with IDPs and illustrate overlooked molecular features shared between IDPs and globular proteins.

Biography: Jin Ryoun Kim is an associate professor in the Department of Chemical and Biomolecular Engineering at New York University (NYU). Prior to his career at NYU, he earned his BS and MS degrees at Seoul National University and his PhD degree at the University of Wisconsin-Madison majoring in chemical engineering, followe

Abstract: Olefins are a key building block of the petrochemicals industry because they are precursor materials for numerous chemical products and plastics. The current commercial production method is steam cracking of ethane followed by cryogenic distillation of olefin/paraffin mixtures, which involves large energy consumption and greenhouse gas footprint. Membranes using facilitated transport show promising olefin/paraffin selectivity due to the presence of carriers that specifically complex with olefins. Unfortunately, facilitated transport-based membranes for olefin/paraffin separation have not been viable because the silver carriers deactivate rapidly in the presence of any H2, which chemically reduces the silver salts to inactive silver metal. While a number of groups have shown that supported ionic liquid (IL)/silver salt membranes (SILMs) and polymer/silver salt membranes show good olefin/paraffin selectivity, we have discovered that some silver salts and ILs provide protection of the silver salts from reduction by H2, leading to stable performance over long times. Our work shows that IL/silver salt mixtures in ceramic supports and polymeric/silver salt composites show excellent olefin/paraffin permeability and resistance to reduction by hydrogen. These innovations pave the way for selective olefin/paraffin separation with dramatically reduced energy consumption, that is viable from laboratory to commercial scale operation.

Biography: Joan F. Brennecke is currently Cockrell Family Chair in Engineering #16 in the McKetta Department of Chemical Engineering at the University of Texas at Austin. She began her academic career at the University of Notre Dame after completing her Ph.D. and M.S. (1989 and 1987) degrees at the University of Illinois at Urbana-Champaign and her B. S. at the University of Texas at Austin (1984).
Her research interests are primarily in the development of less environmentally harmful solvents. These include supercritical fluids and ionic liquids. In developing these solvents, Dr. Brennecke’s primary interests are in the measurement and modeling of thermodynamics, thermophysical properties, phase behavior and separations. Major awards include the 2001 Ipatieff Prize from the American Chemical Society, the 2006 Professional Progress Award from the American Institute of Chemical Engineers, the J. M. Prausnitz Award at the Eleventh International Conference on Properties and Phase Equilibria in Greece in May, 2007, the 2008 Stieglitz Award from the American Chemical Society, the 2009 E. O. Lawrence Award from the U.S. Department of Energy, and the 2014 E. V. Murphree Award in Industrial and Engineering Chemistry from the American Chemical Society. She served as the Editor-in-Chief of the Journal of Chemical & Engineering Data from 2010-2020. Her 200+ research publications have garnered over 22,000 citations (ISI). She was inducted into the National Academy of Engineering in 2012 and served as the Chair of The N