Polylactones.: 55.: A-B-A triblock copolymers of various polypeptides.: Syntheses involving 4-aminobenzoyl-terminated poly(ε-caprolactone) as B block
Polylactones.: 55.: A-B-A triblock copolymers of various polypeptides.: Syntheses involving 4-aminobenzoyl-terminated poly(ε-caprolactone) as B block
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DOI：
10.1021/bm0100561
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发表时间：
2001-12-01
影响因子：
6.2
通讯作者：
Hauser, K
中科院分区：
文献类型：
--
作者：
Kricheldorf, HR;Hauser, K
具有聚合度(DP)约25和两个4-氨基苯甲酰基链端的遥爪聚(ε-己内酯)被用作各种α-氨基酸N-羧酸酐(NCA)的开环聚合的大引发剂。甘氨酸-NCA、L-丙氨酸-NCA、L-苯丙氨酸-NCA和γ-苄基-L-谷氨酸-NCA作为单体，NCA/大分子引发剂比例在20:1、40:1和100:1之间变化。对于 L-Phe-NCA，也使用 200:1 的比例。通过模型研究证明，尽管NCA的亲核性相对较低，但它们可以与4-氨基苯甲酰端基几乎定量地发生反应。分离的三嵌段共聚物通过粘度测量和关于其组成的H-1 NMR光谱进行表征（在大多数情况下与进料比平行）。然而，在γ-Bzl-Glu-NCA的情况下，获得二嵌段共聚物和三嵌段共聚物的混合物。通过红外光谱和 C-13 NMR CP/MAS 光谱检查了固体共聚物的二级结构。研究发现，根据NCA/大分子引发剂的比率，聚(L-Ala)和聚(L-Phe)嵌段的α-螺旋/β-折叠比率随着它们的平均长度而增加。
A telechelic poly(epsilon-caprolactone) having a degree of polymerization (DP) around 25 and two 4-aminobenzoyl chain ends was used as a macroinitiator for the ring-opening polymerization of various a-amino acid N-carboxyanhydrides (NCAs). Glycine-NCA, L-alanine-NCA, L-phenylalanine-NCA, and gamma-benzyl-L-glutamate-NCA served as monomers and the NCA/macroinitiator ratio was varied between 20:1, 40: 1, and 100:1. In the case of L-Phe-NCA, a ratio of 200:1 was also used. It was demonstrated by means of model studies, that the NCAs may react almost quantitatively with the 4-aminobenzoyl end groups despite their relatively low nucleophilicity. The isolated triblock copolymers were characterized by viscosity measurements and by H-1 NMR spectroscopy with regard to their composition (which in most cases paralleled the feed ratios'). However, in the case of gamma-Bzl-Glu-NCA mixtures of di- and triblock copolymer were obtained. The secondary structures of the solid copolymers were examined by IR spectroscopy and C-13 NMR CP/MAS spectroscopy. It was found that the alpha-helix/beta-sheet ratio of the poly(L-Ala) and poly(L-Phe) blocks increases with their average length, according to the NCA/macroinitiator ratio.