No abstract

When a monolayer culture of normal Balb/c3T3 cells is wounded by scraping away part of the cell sheet, the cells do not migrate into the cleared area unless there is serum in the culture medium. (14). The number of cell nuclei crossing the starting line marked on the plate were counted in three 1.7-mm lengths and averaged to give the

No abstract

No abstract

A strategy was developed for the purification of a biologically active polypeptide growth and migration factor from skimmed bovine milk. This 25-kDa dimeric molecule, termed milk growth factor (MGF), was isolated by a method consisting of a combination of strong cation-exchange chromatography, low-pressure hydrophobicinteraction chromatography, hydrophobic-interaction HPLC and size-exclusion HPLC steps, which separated the protein according to its properties of charge, hydrophobicity and size, respectively. On average, a total purification of lo6-107-fold and a yield of approximately 115 78 ng/MGF/milk was obtained using the method described. All purification steps were performed with novel combinations of ethanol and volatile acidic salt (ammonium acetate) solutions in order to retain biological activity of the protein. These conditions, together with the easy removal of salt by lyophilisation, facilitated the detection of biological activity in fractions collected at each step of the purification by means of a sensitive in vitro fibroblast-migration assay in which the half-maximal activity was obtained at a concentration of approximately 17 f 4 pg/ml (i.e. approximately 1 pM) of the pure protein.Biological activity of the dimeric protein was unaffected by heat treatment or exposure to acid (pH 2.0), but was lost upon reduction to its monomeric form. Amino acid composition and sequence analyses demonstrate that MGF is related to transforming growth factor type 82.

No abstract

No abstract

No abstract