Phosphopeptide synthesis

Protein phosphorylation mediated by protein kinases is the principal mechanism by which eukaryotic cellular processes are modulated by external physiological stimuli (1). Phosphopeptides are essential tools for the study of this process, serving as model substrates for phosphatases, as antigens for the production of antibodies against phosphorylated proteins, and as reference compounds for determining their physical parameters. The development of methods for the production of phosphopeptides has consequently attracted considerable interest over the last few years, and these endeavours have yielded reliable procedures which have now made their synthesis routine. 

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Cleavage of the phosphonate allyl esters from Abu[PO(OAl)2]-peptide-resins is accomplished by treatment with Pd(PPh3)4 (50 °C, 5 h)[103l followed by acidolytic deprotection of the Abu[PO(OH)2]-peptide from the resin support. The viability of employing allyl phosphonate protection for phosphopeptide synthesis has been demonstrated by the Fmoc solid-phase synthesis (DIC/HOBt couplings) of several 6-9-mer Abu[PO(OH)2]-containing peptides and has been extended to the synthesis of a 19-mer caldneurin-related Abu[PO(OH)2]-peptide.[104 ... 

The previous section 3.3 on the use of tervalent phosphorus acid derivatives for synthesis of compounds of biological relevance has this year been divided into two parts, 3.3 use for nucleotide synthesis, and 3.4 use for sugar phosphate, phospholipid, or phosphopeptide synthesis. 

Use for Sugar Phosphate, Phospholipid, or Phosphopeptide Synthesis.- A review has been published on the synthesis of phosphorylated biomolecules by the phosphoramidite approach. It contains chapters on sterol-mononucleotide conjugates, mononucleotide glycoconjugates, sugar phosphates, phospholipids, phosphopeptides, and nucleopeptides. 

Fig. 1 Phosphopeptide synthesis on solid support General conditions. (I) monoBAL, HBTU, HOBt DIEA, NMP (II) H-Gly-NHz, NaBHsCN, AcOH-MeOH (1 99) (HI) Fmoc-Gly-OH, DIG. DCM-NMP (9 1) (/v) Fmoc-Aaa-OH, HBTU, HOBt DIEA, NMP (i AC2O, DCM (vl) TRA-TES-H2O (95 2.5 2.5). MM microwave heating, 60 °C Pphosphate group on Ser, Thr, orTyr PEGA poly[acryloyl-bis(aminopropyl)polyethylene glycol] r6Tenta(3el FSpolystyrene [14,15,29]...

Chemoenzymatic Synthesis of a Characteristic Glyco-phosphopeptide from the Transactivation Domain of the Serum Response Factor, J. Sander H. Waldmann, Angew. Chem 1999, 111, 1337-1339, Angew. Chem Int. Ed. 1999,38,1250-1252... 

JS McMurray, DR Colman IV, W Wang, ML Campbell. The synthesis of phosphopeptides. Biopolymers (Pept Sci) 60, 3-31, 2001. 

Example 24 preparation of an asymmetrically-protected phospho-roamidite 0-tert-butyl-0-2-cyanoethyl-iV,iSr-diisopropylphosphoroamidite as a phosphitylating reagent in the synthesis of phosphopeptides has been described by Toth s group. [52]. This reagent allows the efficient synthesis of serine and threoine containing phosphopeptides by the global approach. 

Following the style of presentation used in Imperiali s paper concerning the synthesis of caged phosphopeptides the general route for synthesis of peptides containing 2-nitrophenylethyl-caged phosphoserine-threonine and tyrosine residue is presented below. 

In contrast to the inherent limitations of synthesis in solution, solid-phase peptide synthesis provides a key method for the generation of many large and complex peptides. The application of phosphorylated amino acids to solid-phase methodology has been the subject of particular interest in consideration of the synthetic potential of this approach for the rapid and routine preparation of complex phosphopeptides. Unlike other amino acids, the generation of Ser(F)- and Thr(P)-peptides is complicated due to the sensitivity of these residues to harsh acid or base conditions and the selection of suitable phosphate derivatives that are compatible with solid-phase peptide synthesis. 

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