title: Native chemical ligation between asparagine and valine: application and limitations for the synthesis of tri-phosphorylated C-terminal tau.
abstract: We present the successful native chemical ligation (NCL) at an Asn-Val site employing β-mercaptovaline and subsequent desulfurization in the synthesis of native phosphorylated C-terminal tau, relevant for Alzheimer's disease related research. Despite recent progress in the field of NCL we illustrate limitations of this ligation site that stem from thioester hydrolysis and predominantly aspartimide formation. We systematically investigated the influence of pH, temperature, peptide concentration and thiol additives on the outcome of this ligation and identified conditions under which the ligation can be driven toward complete conversion, which required the deployment of a high surplus of thioester. Application of the optimized conditions allowed us to gain access to challenging tri-phosphorylated C-terminal tau peptide in practical yields.
authors.affiliation: Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin, Germany; Freie Universität Berlin, Institut für Chemie und Biochemie, Takustrasse 3, 14195 Berlin, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Reimann
authors.affiliation: Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin, Germany; Humboldt Universität zu Berlin, Department Chemie, Brook-Taylor-Strasse 2, 12489 Berlin, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Glanz
authors.affiliation: Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin, Germany; Humboldt Universität zu Berlin, Department Chemie, Brook-Taylor-Strasse 2, 12489 Berlin, Germany. Electronic address: hackenbe@fmp-berlin.de.
authors.forename: Christian P R
authors.initials: CP
authors.lastname: Hackenberger
mesh_terms: D000595:Amino Acid Sequence; D001216:Asparagine / Q000737:chemistry*; D008969:Molecular Sequence Data; D010396:Penicillamine / Q000737:chemistry; D010766:Phosphorylation; D013455:Sulfur / Q000737:chemistry; D014633:Valine / Q000737:chemistry*; D016875:tau Proteins / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D016875:tau Proteins; D001216:Asparagine; D013455:Sulfur; D010396:Penicillamine; D014633:Valine
keywords: Aspartimide formation; Ligation at Asn; Native chemical ligation; Penicillamine ligation; Posttranslational modification