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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 23, Number 1
JKCSEZ 23(1)
February 20, 1979 

Changes in Solution Properties of Poly(trans-5-methylproline) During Mutarotation

Poly(trans-5-methylproline)의 변광회전에 따른 용액의 성질변화
Man Jung Han

Poly(trans-5-methylproline) (PTMP)의 변광회전에 따른 CD, ORD 및 uv 스펙트럼의 변화를 관찰하였다. PTMP의 정방향 변광회전은 유기강산이나 trifluoroethanol (TFE) 속에서 일어나며 역방향 변광회전은 TFE용액을 과량의 지방족 알코올로서 회전시킬때 일어났다. 정방향과 역방향 변광회전시의 CD, ORD, 및 uv 스펙트럼의 변화는 polyproline 변광회전시의 변화와 평형하게 일어났다. PTMP의 정방향 변광회전시 αCH-양성자의 화학적이동은 0.3 ppm downfield로 이동하였고 환원 점도는 0.15에서 0.26(dl/g)로 증가하였다 적당한 용매의 혼합물에서는 형태 Ⅰ 과 Ⅱ는 평형을 이루었다. 이러한 모든 용액성질의 변화는 polyproline의 변화와 유사하기 때문에 Ⅰ,Ⅱ의 두 형태는 polyproline 형태 Ⅰ,Ⅱ와 같을 것이며 형태 Ⅰ은 모두 시스아미드 결합을 가진 helix이고, 형태 Ⅱ는 모두 트란스 아미드 결합을 가진 helix일 것이다.

Changes in CD, ORD and uv-spectra during the mutarotation of poly(trans-5-methyl-L-proline) (PTMP) were studied. The forward mutarotion of PTMP occurred in strong organic acids and trifluoroethanol, while the reverse mutarotation was observed by dilution of the trifluoroethanol solution with excess aliphatic alcohols. The changes in CD, ORD and uv-spectra during the forward and reverse mutarotation proceeded paralell to those found for the mutarotation of polyproline. The chemical shift of the αCH-proton was shifted downfield about 0.3 ppm during the forward mutarotation. The reduced viscosity for the forward mutarotation increased from 0.15 to 0.26 (dl/g) during 5 days. The equilibrium between form Ⅰ and form Ⅱ was estabilished in an appropriate solvent mixture. All changes in solution properties mentioned above are similar to those found for polypoline. These results support that the two forms of PTMP are the same conformations as polyproline form Ⅰ and form Ⅱ, i. e., a right-handed helix with all cis amide bonds and a lefthanded helix with all trans amide bonds.

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