Hydrophobic chromatography and fractionation of enzymes from extremely halophilic bacteria using decreasing concentration gradients of ammonium sulfate
Ammonium sulfate fractionation of proteins from an extremely halophilic bacteria [Halobacterium] on Sepharose 4B carboxymethylcellulose, DEAE cellulose and hexamethylenediamine-Agarose is described. Halophilic proteins are adsorbed on these gels at 2.5 M ammonium sulfate and eluted by decreasing concentration gradients of this salt. The method enabled the separation of malate dehydrogenase from glutamate dehydrogenase and aspartate aminotransferase on Sepharose 4B and the additional 15-fold purification of glutamate dehydrogenase on DEAE-cellulose. The technique is simple and convenient, operates at low cost and possesses great power of resolution. The mechanism of adsorption is discussed and compared to previous instances of hydrophobic chromatography. The retention of halophilic proteins on the polysaccharide gels at 2.5 M ammonium sulfate is apparently due to hydrophobic interactions.