Abstract
Collagen is the most abundant protein in mammals and is an important protein in human body. Collagen has been widely used in biomedical materials because of its biocompatibility, low immunity, and biodegradability. In the first part of this thesis, we prepared the collagen mimetic peptides (POG)7-boroncage conjugate, and investigated the delivery of boron into cells for the potential application in boron neutron capture therapy (BNCT). The results show that the boroncage moiety only slightly destabilize the collagen triple helix and the peptide-boroncage conjugate can enter cells. Most of natural collagens are heterotrimers composed of two (AAB) or three (ABC) different peptide chains, and thus studying heterotrimers can better mimic natural collagens. In our early study, we showed that (POG)6(PKG)3 can form heterotrimers with (POG)6(FOG)3 via cation-π interaction. Here we futher added Cys into the N-terminus of (POG)6(PKG)3, CGGG(POG)6(PKG)3, and replaced Gly to Sar, CGGG(POG)5(POSar)(POG) (PKG)3 to study the effects of disulfides and hydrogen bonding on heterotrimers. The results reveal that CGGG(POG)6(PKG)3 is similar to (POG)6(PKG)3 can form AAB-type heterotrimers with (POG)6(FOG)3, and the cation-π interactions could induce the AAB-type heterotrimers. However, neither disulfide-linked CGGG(POG)6(PKG)3 nor disulfide-linked CGGG(POG)5(POSar) (POG)(PKG)3 can form AAB-type heterotrimers with (POG)6(FOG)3. The resulted showed that the disulfide bond at the N-terminus could not facilitate to the folding of collagen heterotrimers and the replacement of Gly to Sar significantly destabilized the triple helix.