Patent ID: 7833397

Claim:
An amino-acid biosensor for measuring a total concentration of a plurality of specific amino acids, comprising a measuring electrode which includes as components a mediator and an enzyme which selectively act on at least said plurality of specific amino acids each serving as a substrate, a counter electrode, and a voltage-current characteristic measurement section, said measuring electrode and said counter electrode being connected to said voltage-current characteristic measurement section to apply a voltage therebetween, wherein: said enzyme has a substrate affinity to each of said plurality of specific amino acids; said enzyme is operable to catalyze a reaction in each of said plurality of specific amino acids as a substrate so as to form a reaction product; said mediator is operable, during amino-acid concentration measurement, to carry electrons between said reaction product and said measuring electrode, and said voltage-current characteristic measurement section applies a voltage between said measuring electrode and said counter electrode during the measurement, which applied voltage includes a voltage that allows a variety of current values for said plurality of specific amino acids at a same concentration and a same applied voltage to fall within about 20% or less of a maximum of said current values at said applied voltage in an analytical curve representing a relationship between said applied voltage and said respective current value at a specific concentration for each of said plurality of specific amino acids, whereby said total concentration of said plurality of specific amino acids is measured by said biosensor.