Protein hormones: detection and extraction of functional forms from alkaline polyacrylamide gels

A method is presented for rapidly staining zones (30 min) in alkaline polyacrylamide gels in the absence of fixatives. Native functional proteins are recovered in homogeneous form after excision of the visible zones from the polyacrylamide matrix. Removal of dye from excised zones is facilitated because only the surface of the gel is stained. Biological activity is then recovered from the gel slices by simple diffusion. The technique makes use of the sensitivity of Coomassie Brilliant Blue G-250 for the detection of proteins (less than 1 microgram). Structural variants of prolactin are isolated and recovered by this method. The method is applicable to studies requiring analytical and semi-preparative electrophoresis of proteins, especially pituitary hormones.