A uremic toxic compound with molecular weight 1007.94 was determined to be an octapeptide by mass spectrometry.Its amino-acid sequence was given as follos: Val-Val-Arg-Gly-Cys-Thr-Trp-Trp.Spin systems for amino acid residues in the octapeptide were identified through analysis of 2D NMR 1H-1H DQF-COSY,TOCSY and ROESY spectra acquired in H2O and D2O.Moreover,the complete assignment of proton resonances for the backbone and side chain was achieved.Based on the secondary chemical shift（Δδ） of the residues,the secondary structure of octapeptide was surveyed.Conformational analyses according to Chemical Shift Index（CSI） showed that the secondary structure of the octapeptide was principally α-helix.The CD spectra of the peptide in aqueous solution gave the same result.Additions of linear polymers made the conformations of octapeptide stretch.These experimental results provide a basis for further comprehension of interaction regulation between biomacromolecule and polymer absorbing materials.
Biodegradable α-hydroxyl polyesters,such as poly(lactic acid)(PLA)and poly(lactic-co-glycolic acid)(PLGA)were investigated as scaffolds for tissue engineering.However,polymeric materials on the basis of lactide are limited in blood vessel engineering due to their poor hydrophilicity and low affinity for the cells.In this study,the functional polylactide with pendant carboxyl(PLMACA)was synthesized,which was expected to improve the blood compatibility and cell adhesion of polyester based on PLA.The structure and composition of PLMACA were confirmed via {}1H NMR spectrum and the compatibilities for blood and cell were stu-{died.} The results show that the PLMACA is hopeful to be used as blood vessel substitute with good HUVEC adhesion and anti-platelet adhesion.
