Heterotrimeric collagen peptides containing functional epitopes. Synthesis of single-stranded collagen type I peptides related to the collagenase cleavage site

Abstract

Synthetic collagen peptides containing larger numbers of Gly-Pro-Hyp repeats are difficult to purify by standard chromatographic procedures. Therefore, efficient strategies are required for the synthesis of higher molecular weight collagen-type peptides. Applying the Fmoc/tBu chemistry, a comparative analysis of the standard stepwise chain elongation procedure on solid support with the procedure based on the use of the synthons Fmoc-Gly-Pro-Hyp(tBu)-OH and Fmoc-Pro-Hyp-Gly-OH was performed. The crude products resulting from the stepwise elongation procedure and from the use of Fmoc-Gly-Pro-Hyp(tBu)-OH clearly revealed large amounts of microheterogeneities that result from incomplete imino acid acylation as well as from diketopiperazine formation with cleavage of Gly-Pro units from the growing peptide chain. Conversely, by the use of the Fmoc-Pro-Hyp-Gly-OH synthon, the quality of the crude products was significantly improved; moreover, protection of the Hyp side chain hydroxyl function is not required using the Fmoc/tBu strategy. With this optimized synthetic procedure, relatively large collagen-type peptides were obtained in satisfactory yields as highly homogeneous compounds.

The Thermodynamics and Kinetics of Collagen Folding

“…Fields proposed the dilysine system to synthesize heterotrimeric peptides of type IV collagen [41] and Moroder used a simplified cysteine bridge to synthesize the collagenase cleavage site of type I collagen [53].…”

Synthesis of heterotrimeric collagen peptides containing the α1β1 integrin recognition site of collagen type IV

“…Taking into account the high tendency of collagenous peptides to self-aggregate into homotrimers and thus, the resulting difficult purification of such highly compact structures by means of chromatographic procedures [27], great care was taken to optimize the synthesis of the single chains [28,29]. The Fmoc/tBu chemistry [30] was selected for assembly of the chains, and the Fmoc-Pro-Hyp(tBu)-Gly-OH synthon was used whenever possible to minimize undesired cleavage of N -terminal dipeptides via diketopiperazine formation in the base-catalysed Fmoc-cleavage steps as reported previously for the synthesis of peptides containing the collagenase cleavage site [21]. However, in contrast to the latter peptides, the target peptide chains exhibit a sequence composition which according to the triplehelical propensity rules [31][32][33] would predict a significantly enhanced tendency to self-aggregation.…”

Cyclotriveratrylene (CTV) as a New Chiral Triacid Scaffold Capable of Inducing Triple Helix Formation of Collagen Peptides Containing either a Native Sequence or Pro-Hyp-Gly Repeats

“…Removal of the Boc group and ester hydrolysis was achieved by acidic treatment, followed by introduction of the Fmoc protection group to give Fmoc-POG-OH (9) in 31% overall yield over five steps. As described by Ottl et al, [11] there is no need for protection of the hydroxy function in hydroxyproline, and the use of this tripeptide building block significantly improved the purity and yield of collagen peptides containing POG repeats.…”

“…179 ± 182 8C (lit. : [11] 177 ± 181 8C); R f 0. 19 Synthesis and analysis of linear peptides: All peptides were synthesized as C-terminal amides by solid phase peptide synthesis on an ABI 433A peptide synthesizer using Argogel Rink-amide resin and the Fastmoc 0.25 mmol protocol.…”