Detail Development of NMR methods for peptide analysis Bibliografi Author: Rogers-Sanders, Sheila Ann ; Larive, Cynthia K. (Advisor) Topik: CHEMISTRY; ANALYTICAL Bahasa: (EN )    ISBN: 0-599-47966-3     Penerbit: UNIVERSITY OF KANSAS     Tahun Terbit: 1999     Jenis: Theses - Dissertation Fulltext: 9946121.pdf (0.0B; 1 download) Abstract Short (less than 20 amino acids) linear peptides often adopt less-ordered structures in solution. In this case, conformational analysis based on the results of NMR experiments is complicated by the presence of rapidly interconverting random coil and ordered structures, which are reflected in the averaging of the NMR parameters (conformational averaging). This dissertation describes the conformational analysis of the short linear peptide hGH (9–19), which is a fragment of human Growth Hormone. The conformation of hGH (9–19) was studied in aqueous solution and in trifluoroethanol using standard NMR experiments, circular dichroism, molecular dynamics and diffusion coefficients. The goal of this study is to use diffusion coefficients measured using pulsed-field gradient NMR to provide information about solvent- and temperature-induced changes in the population of the helical and random coil conformers of hGH (9–19). The results show that diffusion coefficients work reasonably well in this regard. The analysis of complex mixtures is important in drug metabolism and in the pharmaceutical industry in general. NMR is one of the most valuable techniques for structural determination, while HPLC is an effective tool for resolution of complex mixtures. Successful applications of HPLC-NMR have been described. The water resonance must be suppressed in these experiments in order to observe the weaker resonances overlapped by it and to increase the dynamic range even if deuterium oxide is used. Although many solvent suppression strategies have been reported, none are without some limitation. A second goal of this dissertation is to evaluate the use of water attenuation by transverse relaxation (WATR) as a solvent suppression method for HPLC-NMR. The method involves addition of a reagent with labile protons to the solution and adjustment of the pH so that the effective spin-spin relaxation time of the water protons is short due to exchange of protons between the reagent and water. The results show that under optimum conditions the method is more effective than presaturation. Opini Anda Klik untuk menuliskan opini Anda tentang koleksi ini! Lihat Sejarah Pengadaan  Konversi Metadata   Kembali

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