Abstract
Six somatomedin-like peptides were purified from human plasma and Cohn fraction IV by a six-step procedure including ethanol precipitation, reversed-phase extraction, gel filtration, chromatofocusing and reversed-phase HPLC. The apparent iso-electric points (pI) of the major components were 8.2 (Sm III) and 6.3 (Sm V) as expected for IGF-I/SmC and IGF-II resp. The pI-values of the minor components were 9.2 (Sm I), 8.7 (Sm II), 6.7 (Sm IV), and 6.15 (Sm VI). They were composed of single peptide chains with apparent MW (SDS-PAGE) of 6,800 (Sm I, II, IV) and 6,400 (Sm III, V, VI). All peptides were equipotent in a bioassay (SO -incorporation into porcine cartilage) and in a competitive protein binding assay. According to their potencies in various RRA and RIA systems Sm I, II, and III were classified as IGF-I/SmC-like and Sm IV, V, and VI as IGF-II-like. These findings were confirmed by amino acid sequencing of the first 20 N-terminal residues so far. Minor differences, however, were observed. The data provide further evidence for the existence of structural variants of IGF-I/SmC and IGF-II in the human.
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Blum, W., Ranke, M., Bierich, J. et al. 96 STRUCTURAL VARIANTS OF SOMATOMEDINS IN HUMAN PLASMA. Pediatr Res 19, 619 (1985). https://doi.org/10.1203/00006450-198506000-00116
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DOI: https://doi.org/10.1203/00006450-198506000-00116