Left-handed and ambidextrous helices in the gas phase.
We have used ion mobility mass spectrometry to study the effect of d-residues on helix formation in unsolvated alanine-based peptides. The right-handed helix of AC-A15K + H+ is significantly disrupted when five or more of the natural L-residues are randomly replaced with D-residues. On the other hand, when a block of L-residues is replaced with D-residues, an unusual ambidextrous structure with helical segments of opposite chirality is formed. A peptide with all D-residues forms a left-handed helix.
Sudha
Rajagopalan
R
Chemistry Department, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405-7102, USA.
Jarrold
Martin F
MF
D019943:Amino Acid Substitution; D005740:Gases / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D044367:Phase Transition; D017433:Protein Structure, Secondary
D005740:Gases; D010455:Peptides