JBC, Vol. 254, Issue 19, 9651-9656, Oct, 1979
Conformational studies of peptide heart stimulant anthopleurin A. Laser Raman, circular dichroism, fluorescence spectral studies, and Chou-Fasman calculations
H. Ishizaki, R. H. McKay, T. R. Norton, K. T. Yasunobu, J. Lee and A. T. Tu
Sea anemone contain a number of closely related peptide heart stimulants.
In the present investigation, the conformation of anthropleurin A from
Anthopleura xanthogrammica was investigated by laser Raman, circular
dichroism, and fluorescence spectral methods and by the Chou-Fasman method
using sequence data. The recent 13C NMR data of the peptide (Norton, R.S.,
and Norton, T.R. (1979) J. Biol. Chem., in press) provided useful
information for the interpretation of the above-mentioned spectral data.
The results from these spectral methods suggested that anthropleurin A and
the related sea anemone peptides are roughly spherical in shape due to the
presence of some beta-bends, possibly due to a beta-pleated sheet region
and due to the 3 cystine residues in the peptide which exist in the
gauche-gauche-gauche configuration. The sole tyrosine residue is exposed to
the solvent, a finding which has now been confirmed by 13C NMR. The laser
Raman and fluorescence spectral procedures showed that one or more of the
tryptophan residues are buried. Interestingly, the reduction of the native
protein with dithioerythritol did not change the spherical shape even in
the presence of 5 M guanidine HCl and the carboxymethylcysteine derivative
of the peptide was folded even in the presence of the denaturing agent,
guanidine HCl.
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