X-group (possible homology)

296 Sulfite reductase hemoprotein (SiRHP), domains 2 and 4

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Ligands and drugs

1,058

Member domains

186

with ligand contacts (≤ 4 Å)

17.6% of members

184

with DrugDomain annotations

17.4% of members

171

with a DrugBank compound

16.2% 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	6	8.2	0.73×	q = 0.41
Homogeneous non-metal compounds	15	3.6	4.16×	not tested
Lipids and lipid-like molecules	1	1.9	0.54×	not tested
Organic oxygen compounds	1	3.3	0.30×	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
DB02832	SRM	Siroheme	166
DB12529	NO2	Nitrite	12
DB11588	CMO	Carbon monoxide	3
DB03961	CDI	2c-Methyl-D-Erythritol 2,4-Cyclodiphosphate	1

Most frequently bound compounds

PDB ligand	Name	Domains in contact
SRM	SIROHEME	168
SF4	IRON/SULFUR CLUSTER	135
CL	CHLORIDE ION	59
Kmetal	POTASSIUM ION	19
SO3	SULFITE ION	18
H2S	HYDROSULFURIC ACID	17
LImetal	LITHIUM ION	7
NO2	NITRITE ION	6
43Q	(3S)-1,3-dihydroxy-4-{[(S)-hydroxy(phosphonooxy)phosphoryl]oxy}-2-methylbut-2-ylium, carbokation intermediate	3
CMO	CARBON MONOXIDE	3
CYN	CYANIDE ION	3
H6P	(2E)-4-hydroxy-3-methylbut-2-en-1-yl trihydrogen diphosphate	2
MGmetal	MAGNESIUM ION	2
NO	NITRIC OXIDE	2
0CG	prop-2-yn-1-yl trihydrogen diphosphate	1
CAmetal	CALCIUM ION	1
CDI	2C-METHYL-D-ERYTHRITOL 2,4-CYCLODIPHOSPHATE	1
F3S	FE3-S4 CLUSTER	1
FEmetal	FE (III) ION	1
HOA	HYDROXYAMINE	1