A single carboxy-terminal arginine determines the amino-terminal helix conformation of an alanine-based peptide.
Arginine is a stabilizing element in both thermophilic and low molecular weight proteins. Similarly Lys+-->Arg+ substitutions increase the helix content of designed helical peptides. Here we explore this 'arginine effect' by examining how Lys+-->Arg+ substitutions influence the 3(10)-helix-->alpha-helix equilibrium in the helical peptide Ac-(AAAAK)3A-NH2. The unsubstituted sequence contains a significant amount of 3(10)-helix, however, single Lys+-->Arg+ substitutions shift the peptide conformation toward alpha-helix in a position-dependent fashion. The single substitution closest to the carboxy terminus induces the largest conformational change at the helix amino terminus. These findings suggest that a single strategically-placed arginine can exert long range control on helix structure.
Fiori
W R
WR
Department of Chemistry and Biochemistry, University of California, Santa Cruz 95064, USA.
Lundberg
K M
KM
Millhauser
G L
GL
D000595:Amino Acid Sequence; D001120:Arginine / Q000737:chemistry*; D002942:Circular Dichroism; D004578:Electron Spin Resonance Spectroscopy; D008239:Lysine / Q000737:chemistry; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary
D010455:Peptides; C019529:polyalanine; D001120:Arginine; D008239:Lysine