Robert Swoboda

Combined Fmoc-Alloc strategy for a general SPPS of phosphoserine peptides; preparation of phosphorylation-dependent tau antisera

A block method for the solid phase synthesis (SPPS) of serine phosphopeptides has been developed using a combination of Fmoc and Alloc strategies. Alloc-Ser[PO(OCH2CH CH2)2] OH2, prepared in a one pot procedure from Alloc-Ser-OH, was introduced at the N-terminus of a sequence prepared by standard Fmoc-SPPS. Global cleavage of the allyl ester based protecting groups, followed by coupling of a tripeptide fragment, led to the tau phosphopeptide, 1. Using tau phosphopeptides a series of phosphorylation state-dependent antisera to human tau protein have been raised. These antisera are valuable tools for studying the tau protein which is found in an abnormal, hyperphosphorylated form in Alzheimers disease brain.

COMBINED FMOC-ALLOC STRATEGY FOR A GENERAL SOLID PHASE SYNTHESIS OF PHOSPHOSERINE PEPTIDES

Abstract A building block method for the SPPS of serine phosphopeptides has been developed using a combination of Fmoc and Alloc strategies. Alloc-Ser[PO(OCH2CHCH2)2]-OH, prepared in a one-pot procedure from Alloc-Ser-OH, was introduced at the N-terminus of a sequence prepared by standard Fmoc-SPPS. Global cleavage of the allyl ester protecting groups followed by coupling of a tripeptide fragment led to tau phosphopeptide, 1, which was not available by post assembly phosphorylation strategies and is an important epitope of tau phosphoprotein in Alzheimer′s Disease. Fmoc SPPS ← Thr(tBu)-Glu(tBu)-Asn(Trt)-Leu-Lys(Boc)-His(Trt)-Wang + Alloc-Ser[PO(OAllyl)2]-OH ← ← H-Lys-Leu-Gly-Ser(P)-Thr-Glu-Asn-Leu-Lys-His-OH