2.8. Diamine oxidase-containing tissues
Both pea or lentil cotyledon contain high levels of diamine oxidase (DAO). This enzyme catalyses the oxidation of diamines, such as putrescine and cadaverine, producing hydrogen peroxide, which can be measured by amperometry. Botrè et al. (1993) developed a cotyledon-based biosensor able to detect 0.5 μM of each one of these diamines. This research group also developed hybrid biosensors, combining lentil tissue with ornithine decarboxylase (ODC) to measure ornithine or with lysine decarboxylase (LDC) to determine lysine (Fig. 3). The performance of the hybrid biosensorswas similar to
that of conventional bi-enzymatic electrodes.