Synthesis and interfacial behavior of poly(Lys-Tyr-Tyr-Lys).
Poly(Lys-Tyr-Tyr-Lys) was synthesized by polycondensation of the tetrapeptide unit using paranitrophenyl esters. The conformation of poly(Lys-Tyr-Tyr-Lys) is very dependent on its environment. CD spectra in bulk are difficult to interpret owing to the contribution of Tyr residues, but from ir spectra it seems that poly(Lys-Tyr-Tyr-Lys) adopts preferentially an unordered conformation in water. Addition of salts induces a partial transition to a beta structure. The behavior is different at interfaces. When poly(Lys-Tyr-Tyr-Lys) is spread as a film on a water subphase, the shape of the compression isotherm curves is compatible with a stacking of two beta-sheets. On a KCl subphase, the polymer film is more expanded and more compressible, and the isotherm curve resembles that of a polymer in a random conformation. The analysis by CD and ir spectroscopy of transferred monolayers using the Langmuir-Blodgett technique allowed us to confirm and make these data more precise: on a water subphase the spectra are those of an antiparallel beta structure. At the interface of a saline solution the spectra are compatible with a mixture of random coil (largely) and a small content of beta structures.
Maget-Dana
R
R
Centre de Biophysique Moléculaire (CNRS), Orleans, France.
Bolbach
G
G
Trudelle
Y
Y
D000595:Amino Acid Sequence; D002942:Circular Dichroism; D007202:Indicators and Reagents; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D011487:Protein Conformation; D017550:Spectroscopy, Fourier Transform Infrared
D007202:Indicators and Reagents; D010455:Peptides; C093900:poly(lysyl-tyrosyl-tyrosyl-lysine)