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UID:20260806T224208EDT-3794SrEvDB@132.216.98.100
DTSTAMP:20260807T024208Z
DESCRIPTION:Dr. Ansgar Siemer\nDepartment of Chemistry\, Columbia Universit
 y\, New York\n“Solid-State NMR Investigations on Protein-Solvent Interacti
 ons\nand Prion Proteins”\n \nSolid-state NMR is a new tool in structural b
 iology used to\ninvestigate protein systems at atomic resolution that are
 \ninaccessible with other techniques such as X-ray crystallography\nand li
 quid-state NMR. I will present recent solid-state NMR results\non two of s
 uch systems:\nThe first system is antifreeze proteins (AFPs) and their ice
 \nbinding properties. Their ice affinity distinguishes AFPs from\nother so
 luble proteins\, which are\, even in the presence of ice\,\nsurrounded by 
 a hydration shell. We identified the ice-binding\nsurface of type III AFP 
 (AFP III) by measuring 13C chemical\nshift perturbations. Furthermore\, ic
 e-protein cross relaxation as\nwell as cross saturation data confirmed tha
 t AFP III is in\ndirect contact to ice. Using water-protein correlation sp
 ectra\, we\nshowed that AFP III keeps parts of its hydration shell while\n
 binding to ice. Frozen solution solid-state NMR is\, therefore\,\nsuitable
  to measure protein-ice interaction but also the\ninteraction of proteins 
 with their hydration shell in general.\nThe second system is prion protein
 s in their infective amyloid\nconformation. In contrast to disease related
  prions\, functional\nprions are characterized by a gain of function and a
 re beneficial\nin their aggregated prion conformation. I will present stru
 ctural\ndata on two of such prions: The first example is HET-s\, a prion\n
 from a filamentous fungus. HET-s gave solid-state NMR spectra of\nsuch hig
 h resolution that we were able to determine the atomic\nresolution structu
 re of the HET-s amyloid fibrils. The second\nexample is the neuronal isofo
 rm of CPEB from the sea snail Aplysia\,\na key player in long-term memory\
 , which is only active in its\naggregated prion conformation. Although sam
 ples of CPEB did not\ngive the same spectral quality as compared to HET-s\
 , they held some\nsurprises and we were able to determine the dynamical an
 d\nstructural heterogeneity of amyloid fibrils formed by CPEB.\nMandatory 
 for Graduate Students\n
DTSTART:20101109T170000Z
DTEND:20101109T170000Z
LOCATION:McIntyre Medical Building\, CA\, QC\, Montreal\, H3G 1Y6\, 3655 pr
 omenade Sir William Osler
SUMMARY:Biochemistry Seminar - Dr. Ansgar Siemer
URL:/channels/event/biochemistry-seminar-dr-ansgar-sie
 mer-168467
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