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Structural analysis of the carboxyl terminal peptide from human chorionic gonadotropin beta-subunit by
E P Rock1, J Czaplicki, A Milon
1Department of Microbiology and Immunology, Stanford University School of Medicine, CA, USA.
Problem:
Vaccines that target human chorionic gonadotropin (hCG) might be made more effective through greater understanding of the solution three-dimensional structure and behavior of the hormone.
Method:
A 37-amino acid carboxyl terminal peptide of the hCG beta subunit was synthesized, purified, and analyzed by two-dimensional nuclear magnetic resonance spectroscopy.
Results:
Double-quantum filtered correlated spectroscopy data on the peptide in water at 4 degrees C reveals 27 multiplets in the peptide fingerprint region, as expected. A nuclear Overhauser effect spectroscopy spectrum shows several intraresidual peaks in the amide region but lacks clearly assignable interresidual signals.
Conclusion:
By itself in water the carboxyl terminal peptide of hCG lacks defined secondary structure elements and is thus likely a random coil. The presence of beta turns appears possible although neither their existence nor their localization can be confirmed.