Using Different Specific Interactions Meditated Secondary Structure of Polypeptides

• Main Authors: Chi-Jen Chen, 陳啟仁
• Other Authors: Shiao-Wei Kuo
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/58419345313066123260

碩士 === 國立中山大學 === 材料與光電科學學系研究所 === 99 === We have two topics, In the first study, we synthesized three low-molecular-weight poly(glutamate)s—poly( γ-methyl l-glutamate) (PMLG), poly( γ-ethyl l-glutamate) (PELG), and poly( γ-benzyl l-glutamate) (PBLG)—through living ring-opening polymerization of their α-amino acid-N-carboxyanhydride derivatives and then blended them with phenolic resin to control the secondary structures of these polypeptides. Each of the three binary blends exhibited a single glass transition temperature (differential scanning calorimetry) and solid state nuclear magnetic resonance (NMR) spectroscopy], characteristic of a miscible system. The strength of the inter-associative interactions depended on the nature of the hydrogen bond acceptor groups, increasing in the order phenolic/PELG > phenolic/PMLG > phenolic/PBLG, as evidenced through analyses using Fourier transform infrared (FTIR) spectroscopy and the Painter–Coleman association model. The fractions of α-helical conformations (measured using FTIR and solid state NMR spectroscopy) of PMLG and PELG decreased initially upon increasing the phenolic content, but increased thereafter; in contrast, the fraction of α-helical conformations of PBLG increased continuously upon increasing the phenolic contents. Using variable-temperature infrared spectroscopy to investigate the changes in the conformations of the secondary structures of the peptide segments in these three binary blends, we found that the α-helical conformation in these three blend systems correlated strongly with the rigidity of side chain groups, the strength of the intermolecular hydrogen bonding with the phenolic resin, the compositions of phenolic resin, and the temperature. More interestingly, the content of α-helical conformations of the polypeptides in these phenolic/PBLG blends increased upon increasing the temperature. The second topic is synthesized low-molecular-weight poly( γ-benzyl l-glutamate) (PBLG) through living ring-opening polymerization of their α-amino acid-N-carboxyanhydride derivatives and blended them with poly( styrene）(PS), poly (acetoxystyrene) (PAS) and poly(vinyl phenol) (PVPh) to control the secondary structures of these polypeptides. DSC have been used to investigate the miscibility of. FTIR spectroscopies and wide-angle X-ray diffraction (WXRD) spectroscopic analyses provided evidence for the change and specific interactions between (PS, PAS and PVPh) and PBLG. That the secondary structures of polypeptides can be altered through blending with other different Specific Interactions, mediated by hydrogen bonding, dipole–dipole, and π—π Interaction, we investigate strong Specific interactions was found between the side-chain esters of PAS, PVPh, but not found between PBLG and PS, because more weakly with the aromatic rings of PS through intermolecular π—π interactions, so that this latter system is phase separated.