Identification and partial purification of a basic fibroblast growth factor-like growth factor derived from bovine colostrum.
Bovine colostrum that had been collected up to 6 h postpartum was fractionated by ammonium sulfate precipitation, and various fractions were examined for basic fibroblast growth factor activity. Activity that stimulated cell growth was detected in the cream fraction, which was purified by isoelectric focusing and heparin affinity chromatography. Three peaks were eluted from the heparin affinity column at approximately 0.5, 1, and 1.75 M NaCl. Although activity that stimulated cell growth was detected in the second and third peaks, a reaction with antibasic fibroblast growth factor antibody was observed only in the third peak. Fractions in the second and third peaks were examined by SDS-PAGE and Western blot analysis. Activity that stimulated cell growth was detected in the second and third peaks; however, after Western blot analysis using antibasic fibroblast growth factor, only the third peak yielded positive bands at 15 and 28 kDa. These fractions were further subjected to a neutralization test using antibasic fibroblast growth factor antibody. The activity that stimulated cell growth in the second peak was virtually unchanged; however, the activity in the third peak was diminished, showing a relative activity of less than 10% at 1.25 micrograms/ml. Therefore, neutralization of the activity that stimulates cell growth by antibasic fibroblast growth factor antibody suggests that the third peak, which was eluted at approximately 1.5 to 2 M NaCl in heparin affinity chromatography, might be a basic fibroblast growth factor-like growth factor.