title: Recovery of thrombopoietin during purification.
abstract: A thrombocytopoiesis-stimulating factor (TSF or thrombopoietin) was previously purified by a six-step purification procedure. However, the exact quantity of TSF that was recovered, through the various purification procedures, was unknown because of the absence of a method for establishing a unit of measure of TSF. In the present work dose-response relationships on both the crude TSF preparations and on the more highly purified TSF were determined. TSF units were calculated from the dose-response curves. A unit of TSF is defined as the amount of material (mg) that is required to increase the percentages 35S incorporation into platelets of immunothrombocythemic mice by 50% above the baseline. The results of determining the TSF units on the crude TSF preparation indicated that 0.11 unit (U) of TSF/mg protein was present. Results showed that the specific activity of TSF can be increased to about 3.6 U/mg by a single purification procedure using Sephadex G-75 column chromatography. Increased specific activities were obtained by additional purification steps, i.e., DEAE-cellulose column chromatography, SE-HPLC, DEAE-HPLC, and SDS-PAGE. The purified product appears to have a specific activity of about 11,000 U/mg of protein with 0.00003% of the protein and 1.1% of the TSF recovered from the starting material. Establishing a unit of measure for TSF will allow calculations of its degree of purity, provide a method for quantitation of recoveries of activities after various purification procedures, and allow comparisons of results from different experiments and different laboratories.
mesh_terms: D000818:Animals; D002460:Cell Line; D002850:Chromatography, Gel / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002852:Chromatography, Ion Exchange / Q000379:methods; D004591:Electrophoresis, Polyacrylamide Gel; D006023:Glycoproteins / Q000302:isolation & purification*; D006801:Humans; D007668:Kidney; D051379:Mice; D008970:Molecular Weight; D013926:Thrombopoietin / Q000302:isolation & purification* / Q000633:toxicity
chemical_list: D006023:Glycoproteins; D013926:Thrombopoietin