## Abstract The circular dichroism (CD) spectrum of poly‐L‐lysine and poly‐L‐glutamic acid has been investigated in the presence of a small percent of side‐chain blocking groups. The blocking groups benzyl, methyl, and carbobenzoxy show qualitatively similar effects. Less than five mole percent of
Side-chain effect on conformation of ionizable polypeptides in aqueous solution
✍ Scribed by Norio Murai; Shintaro Sugai
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1974
- Tongue
- English
- Weight
- 592 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
Abstract
In order to study the effect of side‐chain length on the conformation of polypeptides, conformational changes of various ionic polypeptides with various lengths of side chain, poly‐N^ε^‐glutaryl‐L‐lysine (PGL), poly‐N^δ^‐glutaryl‐L‐ornithine (PGO), poly‐N^ε^‐succinyl‐L‐lysine (PSL), and poly‐N^δ^‐succinyl‐L‐ornithine (PGO), were investigated by ORD, potentiometric titration, and dilatometric measurements in aqueous solution. The results of optical rotation and potentiometric titration measurements indicate strongly that the α‐helix stability increases in the sequence PSO < PSL ∼ PGO < PGL, which corresponds to increased side‐chain length. The volume change associated with the helix–coil transition also increased in the above sequence. This series of polymers seems to be more hydrophobic compared with poly‐L‐glutamic acid or poly‐L‐lysine, as suggested from the values of enthalpy and entropy changes for coil–helix transitions.
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