Relationship between State of a Thermosensitive Matrix and the Activity of Urease Immobilized in It

A. V. Kukhtin,^1,2 N. L. Eremeev,¹ E. A. Belyaeva,¹ and N. F. Kazanskaya¹

¹Department of Chemical Enzymology, School of Chemistry, Lomonosov Moscow State University, Moscow, 119899 Russia; fax: (7-095) 939-50-12; E-mail: nfk_lab@enzyme.chem.msu.su

²To whom correspondence should be addressed.

Submitted September 23, 1996; revision submitted November 27, 1996.

The effect of temperature on kinetic and equilibrium parameters of urea hydrolysis catalyzed with urease immobilized into a thermosensitive poly-N-isopropylacrylamide gel was studied. The Temperature behavior of the gel--urease system is different from similar systems. After a decrease in the enzyme activity above the critical temperature, the maximal rate of the enzymatic reaction and gel swelling ratio begin to increase Urea hydrolysis catalyzed with immobilized urease and shrinking--swelling of the thermosensitive urease-containing gel depend on each other. Under collapse, gel swelling ratio increases due to the enzymatic reaction. The rate of the enzymatic reaction no longer follows Michaelis--Menten kinetics, and the dependence of the reaction rate on substrate concentration becomes more complicated.

KEY WORDS: enzyme kinetics, urease, urea hydrolysis, thermoreversible hydrogel, thermoregulation of enzyme activity.

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