λ -Benzyl-L-Glutamate Graft Copolymers of Cellulose and Poly[Arylene Ether Sulfone]
作者:
WilliamH. Daly,
Soo Lee,
期刊:
Journal of Macromolecular Science: Part A - Chemistry
(Taylor Available online 1988)
卷期:
Volume 25,
issue 5-7
页码: 705-727
ISSN:0022-233X
年代: 1988
DOI:10.1080/00222338808053394
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
Macroinitiators with primary amino substituents were synthesized by one of the following techniques: a) cyanoethylation of cellulose followed by diborane reduction to produce aminopropylcellulose,1;b) nitration, then SnCl2reduction of poly(arylene ether sulfone), 5, to produce poly(2-aminoarylene ether sulfone),2;c) phthalimidation of 5 followed by hydrazinolysis to yield poly(2-aminomethylarylene ether sulfone),3; and d) LiAlH4reduction of poly(cyanophenylene arylene ether) to poly(aminomethylphenylene arylene ether),4. Heterogeneous grafting of Λ-benzyl-L-glutamate-N-carboxyanhydride, 8, to Polymer1resulted in a nonrandom distribution of amino acid residues; α-helical conformations were detected at low BLG-NCA/NH2ratios (<5 amino acids). Using molar ratios ranging from 1 to 100 of 8, relative to the amine concentration, grafting to Polymers3and4was effected in anhydrous THF at room temperature under homogeneous conditions. If reaction times between 24 and 48 h are utilized, high grafting efficiencies (>80%) are obtained. The conformation of the polypeptide chain was evaluated by NMR and infrared spectroscopy. Polypeptides grafted to Polymers 3 and 4 appeared to adopt the expected conformation for the chain length predicted, i.e., a progression from random coil (<8 amino acids) to β-pleated sheet (8–13 amino acids) to α-helix (> 13 amino acids). The benzyl ester functions on the BLG grafts are subject to direct modification with amine nucleophiles; studies with butylamine correlate reaction conditions with extent of ester vs peptide cleavage. In the presence of 1-hydroxybenzotriazole, aminolysis of the ester is favored and conversions to Λ-amides up to 75% without peptide cleavage are achieved.
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