Stabilization of alkaline phosphatase by chemical modification of carboxymethylcellulose

Alkaline phosphatase is a homodimeric metallic-hydrolase where both Zn2+ an Mg2+ are important for catalysis and stability. The study of carboxymethylcellulose CMC is widely used in many industrial aspects and laboratory due to it is a natural organic polymer that is non-toxic, biodegradable, and biocompatibility. CMC was activated with l-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). CMC was converted into the active form then attached to alkaline phosphatase (ALP) to form covalently conjugated CMC with ALP. The CMC‒ALP was evulated under different pH values (5, 6 and 7) and temperatures (50, 60, 70 and 80 oC). As result of the modified ALP, stabilities were increased at both pH (5 and 7) and temperature (50 and 60 oC). However the activity of the enzyme was decreased after 70 and 80 oC. The CMC–ALP conjugation indicates the improved effect of conjugation on the substrate affinity and catalytic performance of the enzyme due to formation of intramolecular cross-links during the multipoint covalent attachment of polymer chain CMC to the enzyme molecule. In general, that modification of enzymes by the anionic polysaccharide CMC might be a useful method for improving enzyme stability under various denaturing conditions.