X-group (possible homology)

139 Multiheme cytochromes

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Ligands and drugs

674

Member domains

530

with ligand contacts (≤ 4 Å)

78.6% of members

450

with DrugDomain annotations

66.8% of members

442

with a DrugBank compound

65.6% 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)

6.5

Superclasses per 20 proteins

narrower than 68% of the 256 X-groups with enough proteins to compare (median 7.6)

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
Organoheterocyclic compounds	62	9.9	6.29×	q < 0.0001
Homogeneous non-metal compounds	14	13.8	1.01×	q = 1.00
Homogeneous metal compounds	28	31.5	0.89×	q = 0.54
Lipids and lipid-like molecules	6	7.1	0.84×	q = 0.89
Organic oxygen compounds	3	12.8	0.23×	q = 2.2e-3
Organic acids and derivatives	2	9.9	0.20×	q = 6.3e-3
Nucleosides, nucleotides, and analogues	0	17.7	0	q < 0.0001
Miscellaneous inorganic compounds	1	0.1	21×	not tested
Organosulfur compounds	1	1.3	0.76×	not tested
Mixed metal/non-metal compounds	1	1.4	0.74×	not tested
Benzenoids	2	4.7	0.43×	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
DB03317	HEC	Ferroheme C	336
DB18267	HEM	Ferroheme	96
DB12529	NO2	Nitrite	18
DB02580	PG6	Pentaglyme	16
DB04079	HTO	Heptane-1,2,3-Triol	15
DB03619	DXC	Deoxycholic acid	11
DB16426	SO2	Sulfur dioxide	4
DB02043	LHG	1,2-Dipalmitoyl-Phosphatidyl-Glycerole	2
DB03040	NTA	Nitrilotriacetic acid	2
DB07918	HQO	2-heptyl-4-hydroxyquinoline N-oxide	2
DB00141	NAG	N-Acetylglucosamine	1
DB04464	FME	N-Formylmethionine	1
DB15878	MOO	Molybdate	1

Most frequently bound compounds

PDB ligand	Name	Domains in contact
HEC	HEME C	369
CAmetal	CALCIUM ION	155
HEM	PROTOPORPHYRIN IX CONTAINING FE	98
SO3	SULFITE ION	27
DGA	DIACYL GLYCEROL	22
NO2	NITRITE ION	19
PGV	(1R)-2-{[{[(2S)-2,3-DIHYDROXYPROPYL]OXY}(HYDROXY)PHOSPHORYL]OXY}-1-[(PALMITOYLOXY)METHYL]ETHYL (11E)-OCTADEC-11-ENOATE	18
MGmetal	MAGNESIUM ION	17
NAmetal	SODIUM ION	17
HTO	HEPTANE-1,2,3-TRIOL	16
PG6	1-(2-METHOXY-ETHOXY)-2-{2-[2-(2-METHOXY-ETHOXY]-ETHOXY}-ETHANE	16
CU1metal	COPPER (I) ION	12
ISW	{3,3'-[(9S)-8,13-diethenyl-3,7,12,17-tetramethyl-9,10-dihydroporphyrin-2,18-diyl-kappa~4~N~21~,N~22~,N~23~,N~24~]dipropanoato(2-)}iron	12
DXC	(3ALPHA,5BETA,12ALPHA)-3,12-DIHYDROXYCHOLAN-24-OIC ACID	11
Kmetal	POTASSIUM ION	10
SX	SULFUR OXIDE	10
ZNmetal	ZINC ION	8
Y1metal	YTTRIUM ION	7
CL	CHLORIDE ION	6
AZI	AZIDE ION	5