Further characterization of the kinetic folding intermediate of alpha alpha-tropomyosin and of its 142-281 subsequence.
The backbone CD spectrum from 250 to 212 nm for the kinetic folding intermediate of alpha alpha-tropomyosin (alpha alpha-Tm) and nonpolymerizable alpha alpha-Tm was obtained. The spectrum shows that the intermediate is indeed alpha-helical with about 70% of the equilibrium alpha-helix content. Subsequence 142Tm281 of the alpha-tropomyosin chain has five tyrosine residues (at positions 162, 214, 221, 261, 267). Stopped flow CD at the negative peak in the tyrosine spectral region (280 nm) shows that any tyrosine residues that contribute to the spectrum in the region have already reached their final state in the fast phase of folding (< 0.04 s).
Mo
J
J
Department of Chemistry, Washington University, St. Louis, Missouri 63130.
Holtzer
M E
ME
Holtzer
A
A
D002942:Circular Dichroism; D007700:Kinetics; D010446:Peptide Fragments / Q000737:chemistry; D017510:Protein Folding; D014335:Tropomyosin / Q000737:chemistry*
D010446:Peptide Fragments; D014335:Tropomyosin