An alkaloid with a novel structure,named Hypodematine,was isolated from Hypodematium sinense Iwatsuki(belonging to Thelypterdaceae).Its structure was elucidated by means of the ~1H-~1H COSY' ~1H-^(13)C COSY and lo...An alkaloid with a novel structure,named Hypodematine,was isolated from Hypodematium sinense Iwatsuki(belonging to Thelypterdaceae).Its structure was elucidated by means of the ~1H-~1H COSY' ~1H-^(13)C COSY and long-range ~1H-^(13)C COSY spectroscopy to have the skeleton of benzo-aza-cyclooctatetraene with a phenyl substituent.Such basic structure has not been found in the na- tural product before.展开更多
The identification of the ~1H spin system for the S-sulfonated insulin B chain was reported in a previous paper. In this note, the ~1H spin system for the S-sulfonated insulin A chain is reported based upon an absolut...The identification of the ~1H spin system for the S-sulfonated insulin B chain was reported in a previous paper. In this note, the ~1H spin system for the S-sulfonated insulin A chain is reported based upon an absolute value mode of a two dimensional correlation spectrum (2D-COSY), a phase sensitive double quantum spectrum (DQ), RELAYED-COSY (RCT) and a nuclear Overhauser 2D spectrum (NOESY).展开更多
Since the discovery of hF-GRP, several analogs have been synthesized in order to see their effects on the gonadotropin releasing activity, either as agonists or antagonists to this peptide. TF14 is one of these analog...Since the discovery of hF-GRP, several analogs have been synthesized in order to see their effects on the gonadotropin releasing activity, either as agonists or antagonists to this peptide. TF14 is one of these analogs, whose 14th position in the primary sequence is Phe instead of Asn in hF-GRP, while its activity is doubled. 2D-NMR (TOCSY, ROESY) was used to determine the conformation of TF14 in solution. Compared with hF-GRP, the whole peptide is in a non-typical more extended conformation, which may give some due to the relation between structure and function of these two peptides.展开更多
Resonance assignments of the <sup>1</sup>H spectrum of insulin are the basis on which to investi-gate its solution conformation by using NMR method. Owing to the complicated aggregationbehaviour of the mol...Resonance assignments of the <sup>1</sup>H spectrum of insulin are the basis on which to investi-gate its solution conformation by using NMR method. Owing to the complicated aggregationbehaviour of the molecule to give broadened n. m. r. lines, only limited resonance assignmentshave been reported. S-sulfonated A and B chains of insulin gave <sup>1</sup>H spectra with good reso-lutions. Based on the 500 MHz absolute 2D-COSY spectrum and 400 MHz phase sensitiveDQF-COSY, Relayed-COSY and NOESY spectra of B chain recorded in D<sub>2</sub>O, all of thespin system identifications of the non-labile protons in the S-sulfonated B chain of insulinwere reported including the specific resonance assignments of eight residues: B<sub>3</sub>Asn, B<sub>9</sub>Ser,B<sub>16</sub>Tyr, B<sub>22</sub>Arg, B<sub>26</sub>Tyr, B<sub>27</sub>Thr, B<sub>28</sub>Pro and B<sub>29</sub>Lys. The pK values of B<sub>16</sub> and B<sub>26</sub> tyrosineare 10.65 and 10.60 respectively from pH titration.展开更多
文摘An alkaloid with a novel structure,named Hypodematine,was isolated from Hypodematium sinense Iwatsuki(belonging to Thelypterdaceae).Its structure was elucidated by means of the ~1H-~1H COSY' ~1H-^(13)C COSY and long-range ~1H-^(13)C COSY spectroscopy to have the skeleton of benzo-aza-cyclooctatetraene with a phenyl substituent.Such basic structure has not been found in the na- tural product before.
基金Project supported by the National Natural Science Foundation of China, the National Institutes of Health of the U.S. and the British Royal Society.
文摘The identification of the ~1H spin system for the S-sulfonated insulin B chain was reported in a previous paper. In this note, the ~1H spin system for the S-sulfonated insulin A chain is reported based upon an absolute value mode of a two dimensional correlation spectrum (2D-COSY), a phase sensitive double quantum spectrum (DQ), RELAYED-COSY (RCT) and a nuclear Overhauser 2D spectrum (NOESY).
基金Project supported by the National Natural Science Foundation of China.
文摘Since the discovery of hF-GRP, several analogs have been synthesized in order to see their effects on the gonadotropin releasing activity, either as agonists or antagonists to this peptide. TF14 is one of these analogs, whose 14th position in the primary sequence is Phe instead of Asn in hF-GRP, while its activity is doubled. 2D-NMR (TOCSY, ROESY) was used to determine the conformation of TF14 in solution. Compared with hF-GRP, the whole peptide is in a non-typical more extended conformation, which may give some due to the relation between structure and function of these two peptides.
基金a grant (DK-34035) from the National Institutes of Health, U.S.A. and a grant (Biol-85-114) from the National Natural Science Foundation of China. The 500 MHz NMR measurements were taken in the National Institute for Medical Researc
文摘Resonance assignments of the <sup>1</sup>H spectrum of insulin are the basis on which to investi-gate its solution conformation by using NMR method. Owing to the complicated aggregationbehaviour of the molecule to give broadened n. m. r. lines, only limited resonance assignmentshave been reported. S-sulfonated A and B chains of insulin gave <sup>1</sup>H spectra with good reso-lutions. Based on the 500 MHz absolute 2D-COSY spectrum and 400 MHz phase sensitiveDQF-COSY, Relayed-COSY and NOESY spectra of B chain recorded in D<sub>2</sub>O, all of thespin system identifications of the non-labile protons in the S-sulfonated B chain of insulinwere reported including the specific resonance assignments of eight residues: B<sub>3</sub>Asn, B<sub>9</sub>Ser,B<sub>16</sub>Tyr, B<sub>22</sub>Arg, B<sub>26</sub>Tyr, B<sub>27</sub>Thr, B<sub>28</sub>Pro and B<sub>29</sub>Lys. The pK values of B<sub>16</sub> and B<sub>26</sub> tyrosineare 10.65 and 10.60 respectively from pH titration.
