title: Synthesis and beta-conformation of copolypeptides with alternating hydrophilic and hydrophobic residues.
abstract: Copolypeptides with alternating hydrophilic and hydrophobic residues were prepared, and their ability to form beta-structures in aqueous solutions was investigated by circular dichroism. Optically pure samples of poly (Lys-Leu-Lys-Leu) and poly (Leu-Glu-Leu-Glu), obtained via the 2-hydroxyphenyl esters, undergo a coil-to-beta transition in presence of salt. The beta-structures obtained under identical conditions with partially racemized samples of poly (Leu-Lys)Np and poly (Leu-Glu)Np, prepared by polycondensation of the corresponding dipeptide p-nitrophenyl esters, appear to be less regular. Non-alternating poly (Gly-Lys-Leu-Lys-Leu) does not form beta-structures in presence of NaCl as does alternating poly (Lys-Leu-Lys-Leu) indicating that the amino acid sequence can dramatically change the tendency to form beta-structures.
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D004951:Esterification; D008722:Methods; D010455:Peptides / Q000138:chemical synthesis*; D011487:Protein Conformation
chemical_list: D010455:Peptides