Phosphorylation Products of Poly-dl(l)-serine

Abstract

Two phosphorylation products of polyserine are described. The first product was obtained by coupling poly-dl-serine with benzyl phosphoric acid, in the presence of dicyclohexyldiimide, and subsequent debenzylation with anhydrous HBr. The second product was obtained by the phosphorylation of poly-dl-(orl)-serine with chlorophosphoric acid.

The peptide derivative (IV), obtained via a benzyl phosphate intermediate, was shown to consist of approximately equimolar amounts of seryl and O-phosphoseryl residues. All of the phosphorous in this polyserine derivative is bound to the hydroxyl groups of the seryl residues and appears in the form of phosphoric acid monoester.

The phosphorylation of poly-dl-(orl)-serine with chlorophosphoric acid yielded a derivate (VI) containing one phosphate group per each serine residue. An extensive rearrangement of the polypeptide chain occured during the phosphorylation reaction with chlororophosphoric acid as a result of an N to O acyl shift. Approximately 80 percent of the phosphate groups of VI are linked to the α-amino groups of the polyester-polyamide VI, the remaining 20% of the phosphates are linked to the β-hydroxyl groups of the modified peptide.