Isolation from embryonic bovine dental enamel of a polypeptide (E₃) containing as its only phosphorylated sequence, Glu—O‐phosphoserine—Leu

Purification, composition, and31P NMR spectroscopic properties of a noncollagenous phosphoprotein isolated from chicken bone matrix

“…The purified phosphoprotein of chicken bone matrix isolated in this study contains considerably more aspartic and glutamic acids and more phosphoserine than the Es and E 4 phosphoproteins of enamel [24,26]. It also differs significantly from dentin phosphoproteins, which are richer in phosphoserine and aspartic acid, but contain much less glutamic acid [7,27].…”

Identification of organic phosphorus covalently bound to collagen and non-collagenous proteins of chicken-bone matrix. The presence of O-phosphoserine and O-phosphothreonine in non-collagenous proteins, and their absence from phosphorylated collagen

“…Indeed, glutamic acid has been identified as being immediately before the O-phosphoserine residues of the enamel phosphopeptides (Seyer & Glimcher, 1969, 1971, 1977aPapas et al, 1977). Similarly aspartic acid residues appear to be located immediately before O-phosphoserine in the phosphopeptides of bovine dentine (A.…”

“…These data, the very high concentrations of glutamic acid in the phosphorylated peptides, and the pH-stability of the organic phosphorus moiety in intact collagen chains strongly suggest that at least part of the organic phosphorus in collagen is present as phosphorylated glutamic acid. This would indicate that the two major chemically different protein fractions in chicken bone matrix that contain organic phosphorus may represent two distinct metabolic pools of organic phosphorus under separate biological control.Phosphoproteins have been identified as part of the non-collagenous components of the organic matrices of mineralized vertebrate tissues such as enamel (Seyer & Glimcher, 1971;Papas et al, 1977;Seyer & Glimcher, 1977a), dentine Veis & Perry, 1967;Butler, 1972;Butler et al, 1972;Veis et al, 1972;Carmichael & Dodd, 1973;Pieri et al, 1975;Menanteau et al, 1977) and bone (Spector & Glimcher, 1972;Shuttleworth & Veis, 1972) [see Leaver et al (1975b) for a review]. There still exists, however, at least two major points of controversy with regard to bone and dentine: (1) how much, if any, of the phosphorylated protein(s) is covalently bound to the collagen, and (2), if present, Abbreviation used: P,, organic phosphate.…”

“…Phosphoproteins have been identified as part of the non-collagenous components of the organic matrices of mineralized vertebrate tissues such as enamel (Seyer & Glimcher, 1971;Papas et al, 1977;Seyer & Glimcher, 1977a), dentine Veis & Perry, 1967;Butler, 1972;Butler et al, 1972;Veis et al, 1972;Carmichael & Dodd, 1973;Pieri et al, 1975;Menanteau et al, 1977) and bone (Spector & Glimcher, 1972;Shuttleworth & Veis, 1972) [see Leaver et al (1975b) for a review]. There still exists, however, at least two major points of controversy with regard to bone and dentine: (1) how much, if any, of the phosphorylated protein(s) is covalently bound to the collagen, and (2), if present, Abbreviation used: P,, organic phosphate.the nature of the organic phosphate moiety covalently bound to the collagen.…”

Serine phosphate, threonine phosphate and γ-carboxyglutamic acid in normal and experimentally induced, pathologically calcified rat skin (topical cutaneous calciphylaxis)

“…This amino acid composition is quite distinct from the noncollagenous EDTA-soluble proteins of dentin (15) and enamel (9,21,25).…”