Table 1A.

Reactive oxygen species (ROS) include seven radical- and four non-radical ROS; the generation enzymes and subcellular locations are presented. Among radical ROS, superoxide and nitric oxide are the dominant radicals which are generated by 10 enzymes and 4 enzymes, respectively. Among non-radical ROS, hydrogen peroxide, singlet oxygen and peroxynitrite are major ROS which are generated by 11 and 8 reactions, respectively.

Category	Name	Formula	Classification	Generating system	Intracellular organelle	PMID	Ref #
Radicals	Superoxide	O2▪−	ROS	Complex I	Mt	24481843	[122]
				Complex II	Mt	24481843	[122]
				Complex III	Mt	24481843	[122]
				XO	Mt, Px, Cyto	15475499	[30]
				eNOS	Golgi, PM	24180388	[229]
				iNOS	Px	24180388	[229]
				nNOS	SR	24180388	[229]
				CYP	ER, Mt	12605691	[33]
				NOX	NOX1 (Caveolae), NOX2 (Phagosome, PM), NOX3/5 and Duox1/2 (PM), NOX4 (Mt, ER, Nuc)	15475499	[30]
				LOX	Cyto, Nuc	15475499	[30]
Radicals	Nitric oxide	NO▪	RONS	eNOS	Golgi, PM, Mt	22178243, 20388537, 11729179	[29,63,230]
				iNOS	Px	22178243, 12085352	[29,88]
				nNOS	SR	22178243	[29]
				XO	Px	22178243	[29]
Radicals	Nitrogen dioxide	NO2▪	RONS	MPO	Nuc, Cyto, Mt	19298861	[89]
Radicals	hydroxyl radical	OH▪	ROS	Fenton reaction	Mt, Cyto, Nuc, Px	24987008	[31]
				Haber-Weiss Reaction	Mt, Cyto	24987008	[31]
Radicals	peroxyl radical	ROO▪	ROS	LOX	Microsome, Mt, Px, PM	15728540	[96]
Radicals	alkoxyl radical	RO▪	ROS	LOX	Microsome, Mt, Px, PM	15728540	[96]
Radicals	Carbonate radical	CO3▪-	ROS	SOD1	Px	17505962	[97]
				XO	Px	17505962	[97]
Nonradicals	hydrogen peroxide	H2O2∗	ROS	SOD	SOD1 (Cyto, Mt, Nuc, Px), SOD2 (Mt matrix),	17505962	[97]
				MAO	Mt	24987008	[31]
				XO	Mt, Px, Cyto	25678748	[64]
				p66shc	Cyto, Mt	27925481	[39]
				acyl-CoA oxidases	Px	25906193	[32]
				urate oxidase	Px	25906193	[32]
				d-amino acid oxidase	Px	25906193	[32]
				d-aspartate oxidase	Px	25906193	[32]
				l-pipecolic acid oxidase	Px	25906193	[32]
				l-α-hydroxyacid oxidase	Px	25906193	[32]
				polyamine oxidase	Px	25906193	[32]
Nonradicals	peroxynitrite	ONOO−	RONS	–	–	17505962	[97]
Nonradicals	singlet oxygen	1O2	ROS	Photooxygenation	Mt, Cyto	22266568	[106]
				MPO	Cyto	27042259	[105]
				LOX	Px	169247	[104]
				dioxygenase	Px	169247	[104]
				lactoperoxidase	Px	169247	[104]
				CYP	ER	29081894	[107]
				Cytochrome C	Mt	29081894	[107]
				Fenton reaction	Px	26070643	[108]
Nonradicals	hypochlorous acid	HOCl	ROS	MPO	Mt, Cyto, Nuc	27042259, 26632272	[105,111]

Abbreviations: XO—xanthine oxidase, NOS—nitric oxide synthase, CYP—cytochrome P450, NOX—NADPH oxidase, LOX—lipoxygenase, SOD—superoxide dismutase, eNOS—endothelial NOS, iNOS—inducible NOS, nNOS—neuronal NOS, MPO—myeloperoxidase, MAO—monoaminoxidase, Mt—mitochondria, Px—peroxisome, Cyto-cytosol, PM—plasma membrane, ER--endoplasmic reticulum, Nuc—Nucleus, SR--Sarcoplasmic reticulum, ECM—extracellular matrix.

^∗41 specific generation enzymes for hydrogen peroxide and superoxide are also studied in Suppl. Table 1.