L-amino acid dehydrogenase with broad substrate specificity. Catalyzes the oxidative deamination of various L-amino acids, L-Arg and L-Cys being the best substrates in vitro. Likely functions mainly as an L-arginine dehydrogenase in vivo. Probably feeds electrons from L-arginine oxidation and also from the oxidation of other L-amino acids into the respiratory electron transport chain associated to the thylakoid membrane, and does not directly interact with molecular oxygen but donates electrons to the plastoquinone pool. Cannot use D-amino acids as substrates. a plastoquinone + an L-alpha-amino acid + H2O = a 2-oxocarboxylate + a plastoquinol + NH4(+) a plastoquinone + H2O + L-arginine = 5-guanidino-2-oxopentanoate + a plastoquinol + NH4(+) Binds 1 FAD per subunit. Inhibited by Ca(2+) and other cations such as Ni(2+), Co(2+) and Zn(2+). The inhibition by o-phenanthroline and salicylhydroxamic acid suggests the presence of a metal cofactor besides FAD in the enzyme. The L-arginine-stimulated O(2) consumption involving slr0782 is inhibited by inhibitors of the respiratory electron transport chain, such as KCN and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone, which indicates a participation of the cytochrome b6/f complex and of a cytochrome oxidase. Amino-acid degradation; L-arginine degradation. Up-regulated when cells are grown with L-arginine as compared to the growth of cells with nitrate (at mRNA and protein level). The increase is substantially higher in the PsbO-free mutant than in wild-type. Belongs to the flavin monoamine oxidase family.