Continuous assay of neuraminidase activity by a bienzyme system immobilized in an artificial membrane

Lactate dehydrogenase and NANA‐lyase were immobilized in an artificial gelantine membrane. This bienzyme system was used for continuous assay of neuraminidase activity. The K ′ m of the active membrane for lactate dehydrogenase and NANA‐lyase using NADH, pyruvic acid, and N ‐acetylneuraminic acid as substrates were found to be 0.25m M , 0.75m M , and 2.1m M , respectively. The K m of soluble neuraminidase using sialyllactose as substrate was found to be 0.13 m M . The pH optimum for neuraminidase activity was 6.0. At 45°C the reaction rate was higher, and no denaturation phenomena of the immobolized enzymes have been observed. This bienzyme membrane was stable for several weeks stored in the reaction buffer at 4°C.