Purification and characterization of a hormone-like factor which inhibits cholera secretion

A factor which inhibits intestinal hypersecretion induced by cholera toxin was studied. The factor was extracted from intestinal mucosa or pituitary gland of pig. It has an isoelectric point of pH 4.7 +/- 0.1 at 10 degrees C and showed a weak affinity to dextran gel and a strong affinity to agarose gel. From agarose gel the factor was eluted with high concentrations of D-galactose or alpha-methyl-D-glucose, while D-glucose and lactose were less effective. After purification more than 2000 times by isoelectric focusing and gel chromatography, the factor was shown by SDS-polyacrylamide gel electrophoresis to be a protein consisting of subunits of molecular mass 30, 17 and possibly 15 kDa.