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Stability of the helical conformation of random L-alanine–L-lysine copolymers in aqueous solution

✍ Scribed by Hiroyuki Sugiyama; Haruhiko Noda

Publisher
Wiley (John Wiley & Sons)
Year
1970
Tongue
English
Weight
561 KB
Volume
9
Category
Article
ISSN
0006-3525

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✦ Synopsis

Abstract

The potentiometric titration of random copolymers of L‐lysine and L‐alanine containing 0–35% alanine was carried out. The standard free‐energy change for the transition of coil to helix was calculated from the titration curve, and was treated by taking account of first‐neighbor interactions. For uncharged lysine Δ__G__° = −140 cal/mole, and for alanine Δ__G__° = −50 cal/mole in 0.06__M__ NaBr at 25°C, indicating that the alanine helix is thermodynamically less stable than the lysine helix. The randomness in co‐polymerization was confirmed by trypsin treatment.

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