X-group (possible homology)

262 Nitric oxide (NO) synthase oxygenase domain

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Ligands and drugs

1,831

Member domains

1,798

with ligand contacts (≤ 4 Å)

98.2% of members

1,506

with DrugDomain annotations

82.3% of members

1,506

with a DrugBank compound

82.3% of members

Aggregated over all current member domains of this group. Drug annotations come from DrugDomain; buffers and crystallization additives are excluded from the tables below.

Chemical profile

ClassyFire chemical superclasses of the ligands bound by this X-group's proteins, from DrugDomain annotations.

Proteins with classified ligands

Superclasses bound (of 23)

—

Superclasses per 20 proteins

fewer than 20 proteins: too few to compare at equal depth

The raw number of superclasses rises with the number of proteins sampled; the per-20 value compares X-groups at equal depth.

Superclass	Proteins	Expected	Ratio	Significance
Homogeneous metal compounds	8	5.3	1.50×	q = 0.19
Organometallic compounds	2	0.0	129×	not tested
Organosulfur compounds	4	0.2	18×	not tested
Organic nitrogen compounds	5	0.4	14×	not tested
Phenylpropanoids and polyketides	2	0.2	8.87×	not tested
Benzenoids	7	0.8	8.83×	not tested
Organoheterocyclic compounds	9	1.7	5.39×	not tested
Organic acids and derivatives	8	1.7	4.77×	not tested
Homogeneous non-metal compounds	7	2.3	3.00×	not tested
Organic oxygen compounds	5	2.2	2.31×	not tested
Nucleosides, nucleotides, and analogues	1	3.0	0.33×	not tested

enriched (q < 0.05)depleted (q < 0.05)not significantnot tested (expected < 5)

Unit: a protein (UniProt accession) with a ligand-binding domain in this X-group, counted once per superclass. Expected counts use each superclass's frequency across all ligand-binding X-groups; significance is Fisher's exact test with Benjamini–Hochberg correction. Buffers and crystallization additives are excluded. ECOD v295.2; the method follows the ECOD 2027 update, whose published figures used a slightly different artifact filter.

DrugBank compounds

DrugBank	PDB ligand	Name	Domains
DB18267	HEM	Ferroheme	1,492
DB00360	H4B	Sapropterin	1,327
DB02994	CAD	Cacodylic acid	92
DB00125	ARG	Arginine	65
DB00742	MTL	Mannitol	23
DB02234	ITU	S-Ethylisothiourea	23
DB03144	HAR	N(5)-[(hydroxyamino)(imino)methyl]-L-ornithine	23
DB03175	POL	Propyl alcohol	22
DB04400	HBI	7,8-dihydrobiopterin	15
DB02077	DP9	L-N(omega)-nitroarginine-(4R)-amino-L-proline amide	14
DB01997	INE	3-Bromo-7-Nitroindazole	13
DB01821	DP1	L-N(omega)-Nitroarginine-2,4-L-diaminobutyric amide	12
DB07388	AT2	ETHYL 4-[(4-METHYLPYRIDIN-2-YL)AMINO]PIPERIDINE-1-CARBOXYLATE	11
DB02562	H2B	Quinonoid 7,8-Tetrahydrobiopterin	9
DB03317	HEC	Ferroheme C	9
DB04223	NRG	Nitroarginine	9
DB02044	14W	N-[3-(aminomethyl)benzyl]acetamidine	8
DB02207	7NI	7-Nitroindazole	8
DB11588	CMO	Carbon monoxide	8
DB02644	3AR	N-omega-propyl-L-arginine	7

Most frequently bound compounds

PDB ligand	Name	Domains in contact
HEM	PROTOPORPHYRIN IX CONTAINING FE	1,787
ZNmetal	ZINC ION	1,613
H4B	5,6,7,8-TETRAHYDROBIOPTERIN	1,604
CL	CHLORIDE ION	444
GDmetal	GADOLINIUM ATOM	196
CAD	CACODYLIC ACID	91
ARG	ARGININE	66
CAmetal	CALCIUM ION	24
MTL	D-MANNITOL	23
GD3metal	GADOLINIUM ION	22
HAR	N-OMEGA-HYDROXY-L-ARGININE	22
ITU	ETHYLISOTHIOUREA	22
POL	N-PROPANOL	22
NO	NITRIC OXIDE	19
KMI	4-methyl-6-{3-[(methylamino)methyl]phenyl}pyridin-2-amine	18
XFJ	6,6'-(pyridine-3,5-diyldiethane-2,1-diyl)bis(4-methylpyridin-2-amine)	17
XFN	6,6'-[(5-aminobenzene-1,3-diyl)diethane-2,1-diyl]bis(4-methylpyridin-2-amine)	17
HBI	7,8-DIHYDROBIOPTERIN	14
8FD	3-[(2-amino-4-methylquinolin-7-yl)methoxy]-5-[(2S)-2-(methylamino)propyl]benzonitrile	12
DP9	L-N(OMEGA)-NITROARGININE-(4R)-AMINO-L-PROLINE AMIDE	12