Conformations of branched poly(α-amino acids) in solution and at the air—water interface

✍ Scribed by Williot, J. P. ;Ruysschaert, J. M. ;Jaffé, J.

• Publisher: Wiley (John Wiley & Sons)
• Year: 1972
• Tongue: English
• Weight: 439 KB
• Volume: 10
• Category: Article
• ISSN: 0449-2978
• DOI: 10.1002/pol.1972.180101102

✦ Synopsis

Abstract

The validity of Silberberg's hypothesis concerning the conformation of branched polypeptides was tested by studies on solutions and on monolayers. The poly(α‐amino acids) investigated consisted of poly‐L‐lysine backbones with side chains of poly(gamma;‐benzyl L‐gutamate) and poly(β‐benzyl L‐aspartate). In solution, the conformation was studied in the mixed solvent chloroform–dichloroacetic acid. Optical rotatory dispersion measurements demonstrated the existence of a helix–coil transition which is a function of the length of the side chain. A significant “transition curve” appeared between 9 and 15 residues. From the results, it may be assumed that the poly‐L‐lysine backbone is extended in a coiled conformation and the side chains are coiled or helical, depending on the number of glutamate residues. At the air–water interface, a discontinuity in the surface‐pressure curve appears between 9 and 15 residues per side chain. The similarity with the results obtained in solution appears significant; however, this has to be confirmed with methods more specific for structural modifications.