Interaction of water with poly-α-amino acids. II. Relationships between counter-ion and relaxation processes

✍ Scribed by M. Fenton; A. Hiltner

• Publisher: Wiley (John Wiley & Sons)
• Year: 1978
• Tongue: English
• Weight: 472 KB
• Volume: 17
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1978.360171003

✦ Synopsis

Abstract

The effect of hydration on the solid‐state conformation and relaxation behavior of the alkaline earth salts of poly (L‐glutamic acid) has been examined. The calcium and strontium salts take the β‐conformation and the magnesium salt takes the α‐form. No hydration‐dependent conformational transitions were observed. The amount of bound water, as measured by differential scanning calorimetry, appears to depend on the size of the cation, while conformation has little or no effect. A relative measure of the barrier to side‐chain reorientation was obtained from the temperature of the side‐chain (β~1~) relaxation. It was found that the barrier is determined by electrostatic forces and increases with increasing cation surface charge density. Side‐chain motion also appears to be more hindered in the β‐conformation than in the α‐conformation.