Peptide recognition: encapsulation and alpha-helical folding of a nine-residue peptide within a hydrophobic dimeric capsule of a bowl-shaped host.
A dimeric capsule of coordination bowl 1 encapsulated a nine-residue peptide (Trp-Ala-Glu-Ala-Ala-Ala-Glu-Ala-Trp; 2) within the large hydrophobic cavity in water, and stabilized the alpha-helical conformation of bound 2. An NMR titration experiment revealed that monomeric bowl 1 recognized two Trp residues at the both terminals of 2 through 1/2 = 1:1 to 2:1 complexation. The 1:1 and 2:1 species exist in equilibrium even in the presence of excess 1. It was found that the formation of the 2:1 complex, in which two bowls of 1 wrapped the whole of 2, became dominant by the addition of NaNO3 due to the fact that the enhanced ion strength increased the hydrophobic interaction between Trp residues and the cavity of 1. The alpha-helical conformation of 2 within the dimeric capsule of 1 was elucidated from detailed NOESY analysis.
Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656, Japan.
Shohei
S
Tashiro
Masahide
M
Tominaga
Yoshiki
Y
Yamaguchi
Koichi
K
Kato
Makoto
M
Fujita
D019281:Dimerization; D057927:Hydrophobic and Hydrophilic Interactions; D009682:Magnetic Resonance Spectroscopy; D009842:Oligopeptides / Q000737:chemistry* / Q000378:metabolism*; D009942:Organometallic Compounds / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017510:Protein Folding; D017433:Protein Structure, Secondary
D009842:Oligopeptides; D009942:Organometallic Compounds