The thermal induced helix—β transition of poly(Nε-methyl-L-lysine) and poly(Nδ-ethyl-L-ornithine) in aqueous solution

✍ Scribed by Hiroyuki Yamamoto; Jen Tsi Yang

• Publisher: Wiley (John Wiley & Sons)
• Year: 1974
• Tongue: English
• Weight: 380 KB
• Volume: 13
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1974.360130604

✦ Synopsis

Abstract

Uncharged poly(N^ε^‐methyl‐L‐lysine) (PMLL) and its isomer, poly(N^δ^‐ethyl‐L‐ornithine) (PELO), in alkaline solution (pH ca. 12) undergo a helix‐to‐β transition upon mild heating at 50°C or higher in a manner similar to that of poly(L‐lysine) (PLL). The rate of conversion follows the order: PMLL < PELO < PLL. The helix can be regenerated upon cooling near zero degrees, for instance, after more than 12 hr at 2°C. At concentrations less than 0.02% the β form is intramolecular, but at higher concentrations both intra‐ and intermolecular β forms are generated. Poly(N^δ^‐methyl‐L‐ornithine) (PMLO), an isomer of PLL, behaves like poly(L‐ornithine); uncharged PMLO in alkaline solution is partially helical and becomes disordered at elevated temperatures.