Role of N-t-Boc group in helix initiation in a novel tetrapeptide.
Protecting groups in N- and C-terminal positions play a decisive role in the conformational preference of smaller peptides. Conformational analysis of tetrapeptide derivatives containing Ala, Ile and Gly residues was performed. Peptide 1, Boc-Ala-Ile-Ile-Gly-OMe (Boc: tert-butyloxycarbonyl) has a predominantly helical turn conformation in all the alcoholic solvents studied, whereas in the solid state it has a beta-sheet conformation. In contrast, peptide 2, Ac-Ala-Ile-Ile-Gly-OMe (Ac: acetyl) has a random coil conformation in solution. The FTIR spectrum of peptide 1 shows a lower frequency of urethane carbonyl, indicating involvement of the carbonyl group in hydrogen bonding in the helical turn.
Ganesh
S
S
Bioorganic Laboratory, Central Leather Research Institute, Adyar, Chennai, India. karkuvi77@hotmail.com
Jayakumar
R
R
D000595:Amino Acid Sequence; D000682:Amyloid; D002942:Circular Dichroism; D005563:Formic Acid Esters / Q000737:chemistry*; D006860:Hydrogen Bonding; D015394:Molecular Structure; D009842:Oligopeptides / Q000138:chemical synthesis* / Q000737:chemistry*; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared
D000682:Amyloid; D005563:Formic Acid Esters; D009842:Oligopeptides; C000345:t-butyloxycarbonyl group