Synthesis of oligophosphoseryl sequences occurring in casein. Identification of beta-elimination during phosphorylation.
The protected oligophosphoseryl peptides from bovine caseins, Z-Xxx-(Ser[PO(OPh)2])3-Glu(OBzl)-OBzl for Xxx = Ile, Val, Gly, Leu and Ph = phenyl, were synthesized in high yields by stepwise lengthening using Boc-Ser[PO(OPh)2]-OH as acylating carboxyl component and N-ethyl-N'-(3-dimethylaminopropyl)-carbodiimide hydrochloride as coupling reagent. The hydrogenolytic deprotection (PtO2) was carried out with the valine derivative and with the tetrapeptide Ser[PO(OPh)2]3-Glu(OBz)-OBzl. Phosphorylation of oligoseryl peptides failed to give the expected products. Large scale phosphorylation of protected serine was carried out in the presence of triethylamine using absolute ether as a solvent. 2,2,2-Trichloroethyl group (Tc) was shown to be a useful phosphorus protecting moiety in phosphopeptide synthesis: Boc-Ser[PO(OTc)2]-OBzl, Z-Ser[PO(OTc)2]-OBzl and Boc-Glu(OBzl)-Ser[PO(OTc)2]-OBzl were synthesized in high yields using bis-(2,2,2-trichloroethyl) phosphochloridate.
Paquet
A
A
Department of Agriculture, Food Research Centre, Ottawa, Ontario, Canada.
Johns
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M
D000595:Amino Acid Sequence; D002364:Caseins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis*; D010766:Phosphorylation; D010768:Phosphoserine / Q000737:chemistry*
D002364:Caseins; D010446:Peptide Fragments; D010768:Phosphoserine