| Abstract: | We report here preliminary data using reversed-phase high-performance liquid chromatography for the purification of a specific inhibitor (a molecular weight 16,000–18,000 protein) of the insulin-like growth factor (IGF) or somatomedin family. Crude inhibitor prepared from Cohn fraction IV-1 of human serum was first partially purified using an IGF/CH-Sepharose 4B affinity column. Following elution of the bound inhibitor and resuspension in 0.1% aqueous trifluroacetic acid (mobile phase A), it was injected (100 μl; 2.0 mg protein) onto a Brownlee Aquapore RP-300 column. Application of a linear gradient from 0% to 100% mobile phase B (45% isopropanol−0.1% trifluoroacetic acid) resulted in elution of two peaks of inhibitor activity between 31% and 34% isopropanol associated with a major homogeneous protein peak and a minor heterogeneous protein peak. No inhibitor was recovered when an acetonitrile gradient was used instead of isopropanol, indicating that the inhibitor is very hydrophobic. These data suggest that high-performance liquid chromatography offers a simple procedure for the potential purification of IGF inhibitor(s) from normal human serum. |
