Isolation and partial characterization of canine epidermal growth factor/urogastrone

Canine epidermal growth factor (EGF)/urogastrone was partially purified from dog urine by fractional precipitation with (NH4)2SO4, ion-exchange chromatography with DEAE-cellulose DE-52, gel filtration with Sephadex G-50, and a second DE-52 chromatography, to yield receptor-competing activity equivalent to 13 micrograms of standard mouse EGF/litre of starting urine. The purification was monitored by a competitive radioreceptor assay using fixed monolayers of A431 cells. The partially purified canine EGF/urogastrone demonstrated a growth-stimulating activity in 3T3 mouse fibroblast cells as potent as mouse EGF. Analysis by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis revealed one major peptide component with an Mr similar to that of mouse EGF, and two minor peptides of slightly higher Mr. The major peptide component was isolated after reduction and its amino acid composition was determined.