Peptide chain, extension

The nature of the mutational event which could lead to a peptide chain extension can only be guessed at. A mutation in an initiation codon or in the recognition site in the intercistronic region could have been sufficient to form the first zymogen. Alternatively a partial genetic crossover could lead to such an extension. 

After peptide chain extension and disulfide bond formation by oxidative cyclization, the phenylacetyl group could be removed enzymatically in 74% yield. The technique has been applied further in the synthesis of even larger peptides, for example in the deprotection of tris(phenylacetamido)porcine insulin.P l Since PGA is commercially available and devoid of any peptidase activity, this method appears to be generally useful for the construction of lysine-containing oligopeptides. 

The oc-mercaptobenzhydryl linker 27 [71] was developed for the synthesis of thioacids by Boc synthesis. Acylation of the thiol group with Boc-amino acids leads to a resin-bound thioester. Subsequent peptide chain extension and then treatment with HF cleaves the ester-linker bond, releasing the C-terminal peptide thioacid. Unfortunately, owing to the nucleophile lability of thioesters, this approach cannot be applied to Fmoc-based methods. 

Harvey AJ, Abell AD. 2001. a Ketoester based photobiological switches synthesis, peptide chain extension and assay against a chymotrypsin. Bioorg Med Chem Lett 11(18) 2441 2444. 

H-fragmentrOClt Plpoc-tragmenfa-OH Ftiwc-fragmentyfragmentz-OC Figure 5. Peptide chain extension to both C- and N erminal directions. 

The protected Af-(l-deojQ -D-fructopyranos-l-yl)valine (3) was obtained from D-glucose and valine by Amadori rearrangement the dodecapeptide terminal partial sequence of the iJ Chains of HbAjc haemoglobin was then constructed from this by peptide chain extension and deprotection. ... 

Collagens from different tissues do not necessarily contain the same cross-links. In dentin, cross-links occur between two collagen molecules with two or three peptide chains involved. The difunctional didehydro-hydroxylysinonorleucine and didehydro-dihydroxylysinonorleucine, and the trifunctional hydroxylysylpyridinoline and lysylpyridinoline have been demonstrated in human and animal dentin (fig. 1). Fredentin, on the other hand, contains more difunctional and fewer trifunctional cross-links than dentin (Linde and Robins, 1988 Walters and Eyre, 1983 Yamauchi et al., 1992). These cross-links connect the non-helical extension... 

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