Biologically active basic fibroblast growth factor migrates at 27 kD in "non-denaturing" SDS-polyacrylamide gel electrophoresis.

Using mild conditions of SDS-PAGE, i.e. no heating of the sample, and the PhastSystem (Pharmacia), we found that bFGF, either natural bovine or recombinant human migrated at a 27 kD position in addition to the classical 18 kD one. By the cell-blot technique, we found that the biological activity toward rat astroblasts and 3T3 mouse fibroblasts was always restricted to the 27 kD band. Partial heat denaturation experiments revealed a close correlation between the remaining biological activity of bFGF in solution and the ratio of the 27 kD band versus the 18 kD band seen on SDS gels. These observations suggest that the bFGF which is biologically active in solution migrates at an apparent Mr of 27 kD in our conditions of electrophoresis, keeping its biological activity after electrophoresis, and the molecules which are inactive (denatured) in solution migrate at 18 kD and remain inactive. These experimental conditions, in which the biological activity appears to be preserved, could be referred to as "non-denaturing SDS-polyacrylamide gel electrophoresis" and could be useful, associated to cell-blot, for the search and characterization of new growth factors active on cells in culture.