Conformational study of poly(α,β-L-aspartic acid)

✍ Scribed by Vladimír Saudek; Štěpánka Štokrová; Pavel Schmidt

• Publisher: Wiley (John Wiley & Sons)
• Year: 1982
• Tongue: English
• Weight: 465 KB
• Volume: 21
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360211108

✦ Synopsis

Abstract

The conformation of several samples of poly(α,β‐L‐Asp) with a molar fraction of β‐bonds ranging from 0.1 to 0.55 was investigated by means of ir and CD spectroscopy and potentiometric titration and compared with the results obtained previously with poly(α‐L‐Asp). All samples investigated underwent a conformational change induced by changes in their degree of ionization: unpronounced ir absorption of amide V at 650 cm^−1^ was shifted to 620 cm^−1^ and substantially increased on deionization; CD spectra changed with the degree of ionization, passing through an isosbestic point; and the pattern of the titration curves was more complex than that of a simple polyelectrolyte. The conformation developing with the decreasing degree of ionization may be considered to be α‐helix, as deduced according to the analogous behavior of other polypeptides. The extent of the conformational change in the individual samples depends on the molar fraction of β‐bonds: the higher it is, the lower is the helix‐forming ability of the sample.