Table II.
Kinetic parameters of ZmPAO and BSAO.
| Enzyme | Substrate | Tm (°C) | pH | Km (µM) | Specific activity (U/mg pro.) | kcat (S−1) | kcat/Km (S−1 µM−1) |
|---|---|---|---|---|---|---|---|
| ZmPAO | SPM | 25°C | 6.0 | 17.4 | 42.9 | 37.9 | 2.2 |
| ZmPAO | SPD | 25°C | 6.0 | 24.9 | 48.0 | 42.4 | 1.7 |
| ZmPAO | SPM | 37°C | 7.4 | 2.8 | 82.0 | 72.5 | 26.2 |
| BSAO | SPM | 37°C | 7.4 | 28.1 | 1.2 | 3.3 | 0.1 |
ZmPAO was purified from maize as described in the Materials and methods. Kinetic data were obtained at 25 and 37°C at pH 6.0 and 7.4, respectively, in the presence of spermine or spermidine. kcat and Km values were obtained using several concentrations of substrate, and determined from Lineweaver-Burk plots. ZmPAO, maize polyamine oxidase; BSAO, bovine serum amine oxidase; SPM, spermine; SPD, spermidine.