Jüppner H, Schettler T, Giebel G, Wenner S, Hesch R D
Calcif Tissue Int. 1986 Nov;39(5):310-5. doi: 10.1007/BF02555196.
Radioiodination of synthetic human 37-49 osteocalcin requires optimal labeling conditions in order to obtain a maximum of mono- and di-iodinated tracer with little contamination by tri- and tetra-iodinated products or "radio-damage." The antibody raised against osteocalcin(h37-49) had the highest affinity for the C-terminal peptide used for iodination and the larger peptide (h30-49). The intact bovine osteocalcin (b1-49) revealed less immunoreactivity. This C-terminal specific radioimmunoassay detected the intact human osteocalcin in HPLC purified plasma and peritoneal dialysate from patients with terminal renal insufficiency and in extracted human bone. Some quantities of osteocalcin peptides with a higher hydrophobicity were predominantly detected in uremic plasma. These peptides that had a higher molecular weight than the intact human molecule might represent aggregated forms of the intact bone-derived osteocalcin. Immunoreactivity in plasma samples from healthy individuals revealed a remarkable difference as to which substance was employed for anticoagulation. Compared to heparin, the addition of EDTA largely reduced the osteocalcin immunoreactivity, implying that conformational changes within the N-terminal portion (containing the Gla- and Cys-residues) are extended to the C-terminal portion.
合成的人37 - 49骨钙素的放射性碘化需要最佳标记条件，以便获得最大量的单碘化和双碘化示踪剂，同时三碘化和四碘化产物或“放射性损伤”的污染最小。针对骨钙素（h37 - 49）产生的抗体对用于碘化的C末端肽和较大的肽（h30 - 49）具有最高亲和力。完整的牛骨钙素（b1 - 49）显示出较低的免疫反应性。这种C末端特异性放射免疫分析法可检测来自终末期肾功能不全患者的HPLC纯化血浆和腹膜透析液以及提取的人骨中的完整人骨钙素。在尿毒症血浆中主要检测到一些具有较高疏水性的骨钙素肽。这些分子量高于完整人分子的肽可能代表完整的骨源性骨钙素的聚集形式。健康个体血浆样本中的免疫反应性显示，使用哪种物质进行抗凝存在显著差异。与肝素相比，添加EDTA大大降低了骨钙素的免疫反应性，这意味着N末端部分（含有Gla和Cys残基）内的构象变化扩展到了C末端部分。
