N-->O-Acyl shift in Fmoc-based synthesis of phosphopeptides.
Synthetic phosphopeptides are frequently used as chemical probes to explore protein-protein interactions involved in cellular signal transduction. Most commonly, the solid-phase synthesis of phosphotyrosine-containing peptides is performed by applying the Fmoc-strategy and N-Fmoc-protected tyrosine derivatives bearing acid-labile phospho protecting groups. We observed a side-reaction, the isomerisation at threonine, which furnishes depsipeptides. It is shown that the rate of N-->O-acyl migration depends on the sequence context. Depsipeptides were formed most rapidly when the phosphotyrosine was located in the +2 position. Furthermore, different phosphotyrosine building blocks were compared and a suitable method that provides phosphopeptides in enhanced purity and yield is suggested.
Eberhard
Hendrik
H
Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin, Germany.
Seitz
Oliver
O
D000596:Amino Acids / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D020650:Combinatorial Chemistry Techniques; D005449:Fluorenes / Q000737:chemistry*; D007536:Isomerism; D008968:Molecular Conformation; D015394:Molecular Structure; D010748:Phosphopeptides / Q000138:chemical synthesis* / Q000737:chemistry; D013997:Time Factors
D000596:Amino Acids; D005449:Fluorenes; C016456:N(alpha)-fluorenylmethyloxycarbonylamino acids; D010748:Phosphopeptides