Abstract
Collagen is the most abundant protein in mammals and has been widely used in biomedical materials. Searching for an effective way to assemble short collagen mimetic peptides (CMPs) into a high order structure has received many attentions and been an emerging research topic for increasing biomaterial applicability. In the first part of this thesis, we have incorporated histidine (His) into CMPs to promote their self-assembly into supramolecular structures via His-metal coordination. In this study, we used (POG)9 as the parent peptide to design a series of CMPs with His residues incorporated into different positions. Our aim was to investigate the effects of the number and location of His residues on the self-assembly of CMPs. The results showed that incorporting His residues into the ends of a CMP could speed the self-assembly process but the assemblies were less ordered. In contrast, the CMPs without His residues at their ends could assemble into a more ordered and microflorettes like structures though the assembly process was very slow. Although we were not able to clarify the self-assembly process of collagen, we did find the impact of the location of His replacement on the rate of self-assembly and the morphology of assemblies. Our results may be useful and helpful for the future development of collagen-related materials. In the second part of the experiment, we mimicked the active site of zinc metalloenzymes to design metal-CMPs assemblies as catalysts for ester hydrolysis. We used the His residues at both ends of the triple helix as the ligands to coordinate with metal ions and serve as the catalytic active site for ester hydrolysis. It is analogous to the active site of the zinc metalloenzyme carbonic anhydrase (CA). Our results indicated that the catalytic efficiency of the designed peptides was not good at neutral pH, but increased significantly at higher pH values, reflecting the deprotonation of a His side chain. In addition, at pH 9.75 and without the addition of metal, HG(POG)4(PHG)(POG)4GH peptide exhibited an excellent catalytic efficiency, which is three times greater than the previous reported three strained coiled-coils. And these results may be helpful for the development of catalysts for the ester hydrolysis with the collagen triple helix as the based peptide.