合成聚肽嵌段共聚物PHEG-PBLG结构的核磁共振分析

通过L-谷氨酸苄酯和三光气反应制备谷氨酸苄酯的N-羧酸酐，以聚羟乙谷氨酸酰胺为大分子引发剂，投入不同配比的单体/引发剂（A/I）,共聚得到两亲性嵌段共聚物聚羟乙谷氨酰胺-聚谷氨酸苄酯（PHEG-PBLG）；通过核磁共振技术分析表征该合成聚肽的结构组成、分子量范围及螺旋结构；通过体外酶解实验研究了共聚物的降解情况. 研究结果表明：该合成聚肽化合物为两亲性嵌段聚合物：当聚合物中亲水链段PHEG分子量为9000，A/I为75∶1, 100∶1, 150∶1, 200∶1时，相应的共聚物的分子量分别为：1.27×10⁴，1.75×10⁴, 1.9×10⁴, 3.60×10⁴；该合成聚肽含有α-螺旋结构, 随着TFA的加入,该聚肽的结构由α-旋构象转化为随机盘绕构象.

Synthetic Polypeptide Structure of Block Copolymer PHEG-PBLG Analyzed by NMR

Initiated by poly(hydroxylethyl glutamine), amphiphilic block copolymer of poly(hydroxylethyl glutamine (PHEG)) and poly(γ-benzyl-L-glutamate (PBLG)) was synthesized by polymerization of N-carboxyl anhydride (NCA). NCA monomer was synthesized by reacting γ-benzyl-L-glutamate with triphosgene. The constitution, molecular weight and α-helical structures of the resulting block copolymers were studied by NMR and enzymolysis of the black polymers in vitro was discussed. The results showed that the copolymers with different block-ratio of PHEG/PBLG had different molecular weights, being 1.27×10⁴, 1.75×10⁴, 1.9×10⁴ and 3.60×10⁴ when the A/I ratios were 75∶1, 100∶1, 150∶1 and 200∶1, respectively. The copolymers contained α-helix structures in CHCl₃, which could be converted into random coils with addition of TFA.