title: Parameters of helix-coil transition theory for alanine-based peptides of varying chain lengths in water.
abstract: Thermal unfolding curves have been measured for a series of short alanine-based peptides that contain repeating sequences and varying chain lengths. Standard helix-coil theory successfully fits the observed transition curves, even for these short peptides. The results provide values for sigma, the helix nucleation constant, delta H0, the enthalpy change on helix formation, and for s (0 degree C), the average helix propagation parameter at 0 degree C. The enthalpy change agrees with the value determined calorimetrically. The success of helix-coil theory in describing the unfolding transitions of short peptides in water indicates that helical propensities, or s values, can be determined from substitution experiments in short alanine-based peptides.
authors.affiliation: Department of Biochemistry, Stanford University School of Medicine, California 94305.
authors.forename: J M
authors.initials: JM
authors.lastname: Scholtz
authors.forename: H
authors.initials: H
authors.lastname: Qian
authors.forename: E J
authors.initials: EJ
authors.lastname: York
authors.forename: J M
authors.initials: JM
authors.lastname: Stewart
authors.forename: R L
authors.initials: RL
authors.lastname: Baldwin
mesh_terms: D000409:Alanine; D000595:Amino Acid Sequence; D002151:Calorimetry; D008962:Models, Theoretical; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D013329:Structure-Activity Relationship
chemical_list: D010455:Peptides; D000409:Alanine