SYNTHESIS AND PROPERTIES OF BETA-D-GLUCOSIDASE PHENOLIC COPOLYMERS AS ANALOGS OF SOIL HUMIC-ENZYME COMPLEXES

Several .beta.-D-glucosidase-phenolic copolymers were synthesized and 3 examined in detail: those containing L-tyrosine, pyrogallol and resorcinol. These copolymers were similar to naturally-occurring soil humic-enzyme complexes in many ways: E4/E6 ratios, C, H, N and S content and IR spectra. The enzyme activity of the copolymers showed varying degrees of resistance to proteolysis, organic solvents and storage at high temperatures. All immobilized enzymes had increased Km values and decreased Vmax values in comparison with soluble .beta.-D-glucosidase (9.3 mM, 190 .mu.mol p-nitrophenol mg-1 h-1); the .beta.-D-glucosidase-resorcinol copolymer was the most active (10.5 mM, 104 .mu.mol p-nitrophenol mg-1 h-1). .beta.-D-Glucosidase activity was completely resistant to protease when the copolymer was fixed to bentonite clay but Vmax values were reduced further (e.g., .beta.-D-glucosidase-resorcinol-bentonite complex, 58.5 .mu.mol p-nitrophenol mg-1 h-1). On addition to soil, soluble .beta.-D-glucosidase was rapidly inactivated (38% loss in 3 days, 80% loss in 21 days) whereas .beta.-D-glucosidase-resorcinol/pyrogallol and .beta.-D-glucosidase-L-tyrosine copolymers were comparatively stable (no loss in 9 days, 25 and 44% loss in 21 days). It is suggested that the copolymerization of enzyme during humic matter formation is a major factor leading to the stabilization of soil enzymes and that adsorption and entrapment are comparatively insignificant.