Jan 13, 1976

Conformation of gonadotropin releasing hormone

Biochemistry
S Mabrey, I M Klotz

Abstract

The conformation of the gonadotropin releasing hormone (Gn-RH), whose primary sequence is pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-GlyNH2, and of several of its structural analogues has been studied by circular dichroism, optical rotatory dispersion, and fluorescence spectroscopy. The effects of pH, guanidine, and temperature on fluorescence emission have also been examined. Titration data demonstrate that the histidine and tyrosine residues are free of any mutual interactions. The similarity of emission spectra in water and in guanidine hydrochloride solutions precludes significant interactions between the fluorescent groups and other residues. Neither the temperature nor the pH profiles of the emission intensities of either tyrosine or tryptophan reveal any fixed secondary structure in Gn-RH. Both the extent of alkaline quenching and the distance of 10-11 A calculated from Förster energy transfer theory are in accord with a randomly coiled structure with only one residue between tyrosine and tryptophan. Furthermore, the circular dichroism spectrum and optical rotatory dispersion do not exhibit any contributions from peptide bonds in an ordered structure, although there is a perturbation of the peptide absorption region due to ove...Continue Reading

  • References21
  • Citations14

References

Mentioned in this Paper

Tryptophan
Energy Transfer
Optical Rotatory Dispersion
Histidine
Structure-Activity Relationship
Hypothalamic Releasing Factor
Pituitary Gonadotropins
Fluorescence Spectroscopy
Fluorescent stain
Protein Conformation

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