A CD study of the alpha-helix nucleation hypothesis.
One of the dilemmas in predicting the secondary structure of proteins from their amino acid propensity for a given conformation is the presence of all amino acids in all types of secondary structure, regardless of their propensity for that specific structure. One explanation is the nucleation hypothesis that only a few residues with a strong propensity for the secondary structure, such as the alpha-helix structure, initiates its formation and propagates the structure through indifferent sequences until strong breakers terminate the growth on both ends. Eight 15-mer peptides were studied to examine the alpha-helix nucleation hypothesis. The nucleation sequence of VAEAK, with high helix propensity, was mixed with an indifferent sequence of TSDSR in all possible permutations. From the percent alpha-helix structure derived from the CD at 222 nm, it appears that helicity does not propagate through the indifferent sequence.
Toumadje
A
A
Department of Biochemistry and Biophysics, Oregon State University, Corvallis 97331.
Johnson
W C
WC
D000595:Amino Acid Sequence; D002942:Circular Dichroism; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary