Abstract：
:Two terminally blocked peptides, acetylAETAAAKFLRQHMamide and acetylAETSSSRYLRQHMamide, were obtained by solid-phase synthesis, purified by reversed-phase chromatography, and characterized by fast atom bombardment mass spectrometry. Both peptides were soluble in aqueous solutions and remained monomeric over the concentration range examined. Changes in the temperature, pH, and trifluoroethanol concentration of solutions of each peptide produced changes in the far-ultraviolet circular dichroic spectrum characteristic of a two-state helix/coil transition. The limiting mean residue ellipticity of the coil and helix form of each peptide was estimated by addition of the denaturant guanidinium chloride at elevated temperature and by addition of trifluoroethanol at subzero temperatures, respectively. The midpoint for the thermal transition of the peptide SSSRY is lowered by about 30 degrees C relative to that of peptide AAAKF, in qualitative agreement from predictions based on helix probabilities of amino acid residues. The magnitude of the change observed in the midpoint of the thermal transitions suggests that the effect of single amino acid replacements on helix formation should be experimentally measurable.
journal_name
Biochemistryjournal_title
Biochemistryauthors
Merutka G,Stellwagen Edoi
10.1021/bi00427a048subject
Has Abstractpub_date
1989-01-10 00:00:00pages
352-7issue
1eissn
0006-2960issn
1520-4995journal_volume
28pub_type
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