Introduction Flavoprotein oxidases catalyze the oxidation of a wide range of compounds, while at the same time they reduce oxygen to hydrogen peroxide. They are valuable biocatalysts for the oxidative activation of biomolecules, as they usually selectively oxidize their substrate at a specific position, leaving other positions unaffected. Due to their ability to use molecular oxygen as electron acceptor, no expensive coenzymes like NAD(P)H are needed. This makes oxidases inexpensive and rather straightforward in usage compared to other redox enzymes. Aspergillus niger 1992 Peniophora gigantea 2000 2001 A. niger 2005 2006 Escherichia coli 2007 2007 E. coli 2002 Rhodococcus erythropolis Rh Micrococcus rubens Mr 1993 Rh E. coli Materials and methods Chemicals E. coli R. erythropolis Plate-based screening method for oxidase activity R. erythropolis 2002 R. erythropolis Sau Bam E. coli E. coli w v l d d d Sequence analysis Eco http://www.ncbi.nlm.nih.gov/gorf/gorf.html Rh http://www.ncbi.nlm.nih.gov/BLAST Rh puo Rh R. erythropolis Rh CAT ATG Nde Rh AAGCTT TCA Hin Nde Hin Myc puo Rh puo Rh 2 E. coli E. coli puo Rh w v E. coli puo Rh Rh Enzyme purification E. coli puo Rh w v Rh Rh Rh Enzyme activity assay and determination of steady-state kinetic parameters Rh 1975 2 2 Rh ɛ 420 −1 −1 1997 ɛ 515 −1 −1 Rh Rh Rh 2 2 ɛ 420 −1 −1 Influence of temperature and pH on enzyme activity and stability Rh Rh The pH optimum for putrescine oxidase was determined by measuring the activity at different pH values at 25°C. The following buffers were used: 50 mM Pipes buffer (pH 6.4–7.2), 50 mM Tris–HCl (pH 7.4–8.8), and 50 mM Ches buffer (pH 8.7–9.6). The enzyme activity was measured using the HRP-AAP/DCHBS assay. Inhibition experiments Rh 2005 Rh Rh Rh K M Rh K I 1 \documentclass[12pt]{minimal}
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\begin{document}$$K_{{\text{M,inhibitor}}}  = K_m  \cdot \left( {1 + \frac{{\left[ I \right]}}{{K_I }}} \right)$$\end{document} I K M,inhibitor K I Analytical methods Rh Modeling and mutant construction 2004b Rh Rh Rh GCG Rh CGC Rh Rh CTG Rh CAG E. coli Rh Nucleotide sequence accession number Rh puo Rh Results Identification of a novel putrescine oxidase R. erythropolis E. coli Eco Pvu M. rubens 1993 Rh Rh Gene cloning, overexpression, and protein purification Rh Myc puo E. coli L 1997 Rh Rh 1 1 puo Rh 1998 Fig. 1 Rh Lane A Rh Lane B Rh Rh Lane C  Rh Rh 2 Rh Rh Mr Rh Rh 2 2 Rh ɛ 459 −1 −1 1983 459 Mr 1972 Rh Rh Fig. 2 Rh solid line dashed line Rh dotted line  Temperature and pH dependence of activity and stability Rh Rh Substrate specificity Rh 1 k cat K M n 2 Rh Rh Rh Rh K I l Rh Table 1 Rh  ND a Micrococcus rubens 1980 Table 2 Rh  a Micrococcus rubens 1976 Rh Rh 1999 2004b Rh Rh Rh 2004a Rh 3 2006 2002b Rh Rh Rh Rh Rh Mr Mr 1976 Rh Rh Rh Rh Rh 3 Fig. 3 Rh Rh  Table 3 Rh   K m k cat −1 k cat K m −1 −1 Rh 3.5 ± 0.6 20.7 ± 1.1 5900 Rh 110,000 ± 20,000 6.1 ± 0.4 0.05 Rh 110,000 ± 20,000 3.2 ± 0.2 0.03 Rh 2 n Rh Rh Rh 1 k cat K M n −1 −1 Rh Discussion R. erythropolis 2002 E. coli 1984 R. erythropolis 1992 Rh Mr Rh 1 Rh Mr Rh Mr Rh Mr K m Mr 1976 1979 Rh Mr Rh Mr 1999 1999 Rh, Rh 2005 2002a 1999 2006 2007 1995 Rh Electronic supplementary material Below is the link to the electronic supplementary material.
 ESM 1 Rh gray MAO-B PuO Rh Rhodococcus erythropolis PuO Mr Micrococcus rubens .