DEVELOPMENT OF LONG-LIFE LACTATE SENSOR USING THERMOSTABLE MUTANT LACTATE OXIDASE

We examined a long life lactate sensor that employs two types of therm ostable mutant lactate oxidase, both generated by random mutagenesis. One of the mutants, LOD15, exhibits an Asn to Asp point mutation at po sition 212, and the other, LODN1, exhibits a Glu to Gly point mutation at position 160 in the amino acid sequence. These LODs are shown to b e more thermostable than wild-type LOD at 65 degrees C, and their over all inactivation curve at 65 degrees C is less steep. Although LOD15 l actate sensor output is higher than that of a wildtype LOD sensor at 2 4 degrees C, over time during storage at 40 degrees C, this output dec lines significantly. LODN1 sensor output, on the other hand, shows goo d linearity, and its output over the same storage time is about twice as high as that of a wild-type LOD sensor. (C) 1998 Elsevier Science S .A. All rights reserved.