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The Adsorption and Reactions of Enzymes and Proteins on Kaolinite. II¹

The Action of Chymotrypsin on Lysozyme

ABSTRACT

Some preliminary data illustrating the role of adsorption of enzymes and proteins to kaolinite in enzyme-substrate reactions are presented. The adsorption of trypsin and chymotrypsin on kaolinite is nearly complete within 2–3 minutes. Over 40 mg. of chymotrypsin (MW 27,000) is adsorbed per gram of kaolinite whereas only 28 mg. of lysozyme (MW 15,000) is adsorbed. Much less chymotrypsin is adsorbed on kaolinite previously nearly covered by lysozyme. Heat-inactivated lysozyme either in solution or adsorbed on kaolinite is subject to hydrolysis by chymotrypsin. The rate of hydrolysis is slower in the adsorbed state, however. Adsorbed trypsin is slowly hydrolyzed by free trypsin in a suspension of kaolinite. Thus substrates adsorbed on kaolinite are subject to hydrolysis by enzymes in solution. Lysozyme and trypsin eluted from kaolinite with ethylamine are active as enzymes. The possible significance of such findings for an understanding of the microbial utilization of macromolecules in the presence of clay minerals is discussed.

¹ Contribution from the Department of Soils, University of California, Berkeley. Presented before Division III, Soil Science Society of America, Dallas, Tex., Nov. 18, 1953.

² Associate Professor of Soil Chemistry.

Received for publication November 27, 1953.