California State University, Northridge WordmarkOviatt Library WordmarkOviatt Library Catalog Wordmark
Author Kim, William, author.
Title Intermediate timescale exchange in apo TrkB receptor provides insight into the role of molecular motions in its binding selectivity for neurotrophin signaling proteins / by William Kim.
Published [Northridge, California] : California State University, Northridge, 2012.
 Electronic Book  QD40 .Z952 2012 K56eb    ONLINE
Description 1 online resource (xviii, 117 pages)
Content Type text
Format online resource
File Characteristics text file PDF
Thesis M.S. California State University, Northridge 2012.
Bibliography Includes bibliographical references (pages 112-115).
Summary Trk receptors are transmembrane proteins that are expressed widely throughout the nervous system. Interactions with extracellular growth factors known as neurotrophins are responsible for the growth and survival of neurons via signal transduction pathways. Initiation of signaling occurs via binding of a neurotrophin to extracellular domain 5 of its cognate Trk receptor. Neurotrophin malfunction has been implicated in neurological diseases such as Alzheimer's and Parkinson's. Since neurotrophins themselves make poor therapeutics (short lifetime in vivo), the design and development of drugs that mimic neurotrophins is of great importance. The design of such selective neurotrophin agonists, however, will depend on a thorough, molecular level understanding of the interactions between these proteins and their Trk receptors. This project focuses on human tropomyosin receptor kinase B domain 5 (hTrkB-d5); the author is particularly interested in this receptor since TrkB uniquely displays high affinity yet promiscuous binding to two different neurotrophins (specifically, BDNF and NT-4/5). Recently published models of protein binding describe proteins as flexible structures that constantly sample numerous conformations; once a protein binds its ligand, however, its conformational flexibility changes and usually becomes restricted. As such, the flexibility of a protein directly affects the conformations allowed by that protein, and therefore its binding properties. The author hypothesizes that the flexibility of the hTrkB-d5 protein is responsible for the unique binding properties observed. The author used nuclear magnetic resonance (NMR) spectroscopy to search for evidence of molecular motions in hTrkB-d5 and to obtain preliminary insight into the roles they play in selective molecular recognition. A protocol to prepare highly purified, stable, and concentrated 13C/15N labeled hTrkB-d5 was developed. A two-column Fast Protein Liquid Chromatography (FPLC) purification was optimized to isolate hTrkB-d5 after expression in E. coli, yielding 2.3 mg pure hTrkB-d5 per liter of culture. NMR chemical shift assignment experiments were performed, resulting in the partial assignment of peptide backbone atoms in 60 of the 103 total amino acids in hTrkB-d5. Residues for which chemical shifts could not be assigned were due to peaks missing from the spectra; this can be attributed to protein flexibility in those regions. When NMR data from apo hTrkB-d5 was mapped onto a structure of hTrkB-d5 in complex with NT-4/5, residues with missing peaks in the spectra could primarily be mapped onto the surface that binds neurotrophins. The localization of these residues to the binding interface suggests that intermediate timescale conformational exchange in hTrkB-d5 mediates neurotrophin binding. Future hydrogen exchange and relaxation experiments will provide more insight into the role of molecular motions in the unique selectivity of hTrkB-d5 binding to neurotrophins.
Note Description based on online resource; title from PDF title page (viewed on June 01, 2012).
Subject Nuclear magnetic resonance spectroscopy.
Local Subject Dissertations, Academic -- CSUN -- Chemistry and Biochemistry -- Biochemistry.
OCLC number 849914044