The quantification of gammacarboxyglutamic acid residues in plasma-osteocalcin

Berry A.M. Soute, Magda M.W. Ulrich, Marjo H.J. Knapen, L. Johan M. van Haarlem, Cees Vermeer*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


In this paper we describe an assay procedure for determining the amount of gammacarboxyglutamic acid (Gla) residues in serum- or plasma-osteocalcin. The test includes removing by ethanol precipitation the majority of the proteins from the plasma (e.g., the Gla-containing coagulation factors) and the specific extraction of osteocalcin with the aid of immobilized immunopurified antibodies. It is demonstrated that the Gla-content of circulating osteocalcin from normal cows is similar to that of osteocalcin obtained from bone. Hence, the fact that part of the newly synthesized osteocalcin does not bind to the hydroxyapatite matrix in bone cannot be explained by an undercarboxylation of the molecule.

Original languageEnglish
Pages (from-to)184-188
Number of pages5
JournalCalcified Tissue International
Issue number3
Publication statusPublished - 1 Sep 1988

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