ADSORPT ION OF PROTEINS, ENZYMES AND ANTIBIOTICS BY MONTMORILLONITE by

Proteins interact with montmorillonite forming mono- and poly-layer complexes. About 20 percent of the protein in a monolayer complex undergoes microbial decomposition a d the X-ray pattern remains unchanged, whereas in polylayer complexes the protein undergoes extensive decomposition a d the c-spacings ofthese complexes shrink from approximately 30 • to 12/~+. Urease is adsorbed completely by H-montmorillonite and only partially by basic montmorillonite. Initial release of urease from the clay is attributed tourea acting as a cation. Subsequently he ammonia evolved by the hydrolysis of urea becomes the active cation. Antibiotic-montmorillonite complexes are classified into three groups. Group I contains trongly basic antibiotics, II amphoteric, and III acid or neutral. The average adsorption of antibiotic in mg per g of clay for each group is: I, 186; II, 307; and III, 9. X-ray diffraction data for groups I and II showed expansion ofthe c-spacing of4.4 and 7.6 A, respectively. Bioassays showed no activity for I and appreciable activity for II. The com-plexes are incapable of diffusing through agar, but the antibiotics must be released first by cationic exchange and then diffuse through the agar