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290  structures 8212  species 0  interactions 42197  sequences 304  architectures

Family: CN_hydrolase (PF00795)

Summary: Carbon-nitrogen hydrolase

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Carbon-nitrogen hydrolase Provide feedback

This family contains hydrolases that break carbon-nitrogen bonds [1]. The family includes: Nitrilase EC: Q42965 Aliphatic amidase EC: Q01360 Biotidinase EC: P43251 Beta-ureidopropionase EC: Q03248. Nitrilase-related proteins generally have a conserved E-K-C catalytic triad, and are multimeric alpha-beta-beta-alpha sandwich proteins [2].

Literature references

  1. Bork P, Koonin EV; , Protein Sci 1994;3:1344-1346.: A new family of carbon-nitrogen hydrolases. PUBMED:7987228 EPMC:7987228

  2. Pace HC, Brenner C; , Genome Biol 2001;2:REVIEWS0001.: The nitrilase superfamily: classification, structure and function. PUBMED:11380987 EPMC:11380987

Internal database links

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR003010

The carbon-nitrogen hydrolase domain is an around 265-residue domain found in numerous enzymes involved in the reduction of organic nitrogen compounds and ammonia production. Based on their sequence similarity and on the reactions they catalyse, these enzymes can be classified into functionally distinct groups including [ PUBMED:7987228 , PUBMED:12054553 ]:

  • Nitrilases ( EC ), which cleave various nitriles into the corresponding acids and ammonia.
  • Cyanide hydratase ( EC ) of pathogenic fungi, which detoxifies HCN that is released by their hosts, cyanogenic plants, after injury.
  • Aliphatic amidases ( EC ), which enable prokaryotes to use acetamides as both carbon and nitrogen source.
  • Beta-ureidopropionase (also known as beta-alanine synthase or N-carbamoyl-beta-alanine amino hydrolase; EC ), which catalyses the last step of pyrimidine catabolism.
  • Glutamine-dependent NAD(+) synthetase (also known as AdgA, for ammonia-dependent growth) from Rhodobacter species ( EC ). It appears to be essential for using various amino acids as nitrogen sources.
  • Biotinidase ( EC ), which catalyses the hydrolysis of biocytin to biotin and lysine.
  • Pantetheinase ( EC ) (Pantetheine hydrolase) (Vanin), which hydrolyzes specifically one of the carboamide linkages in D-pantetheine, thus recycling pantothenic acid (vitamin B5) and releasing cysteamine.
  • Apolipoprotein N-acyltransferase ([intenz:2.3.1.-]) (gene lnt), a bacterial enzyme that transfers the fatty acyl group on membrane lipoproteins.
  • Glutamine-dependent NAD(+) synthetase ( EC ), which catalyses the final step in NAD+ synthesis [ PUBMED:12771147 , PUBMED:12898714 ].

The carbon-nitrogen hydrolase domain is characterised by several conserved motifs, one of which contains a cysteine that is part of the catalytic site in nitrilases. Another highly conserved motif includes a glutamic acid that might also be involved in catalysis [ PUBMED:7987228 ].

Gene Ontology

The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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We store a range of different sequence alignments for families. As well as the seed alignment from which the family is built, we provide the full alignment, generated by searching the sequence database (reference proteomes) using the family HMM. We also generate alignments using four representative proteomes (RP) sets and the UniProtKB sequence database. More...

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We make a range of alignments for each Pfam-A family. You can see a description of each above. You can view these alignments in various ways but please note that some types of alignment are never generated while others may not be available for all families, most commonly because the alignments are too large to handle.

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Representative proteomes UniProt

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You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

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HMM logos is one way of visualising profile HMMs. Logos provide a quick overview of the properties of an HMM in a graphical form. You can see a more detailed description of HMM logos and find out how you can interpret them here. More...


This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.

Note: You can also download the data file for the tree.

Curation and family details

This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.

Curation View help on the curation process

Seed source: Pfam-B_1042 (release 2.1) & Pfam-B_5155 (Release 7.5)
Previous IDs: Nitrilase;
Type: Family
Sequence Ontology: SO:0100021
Author: Bateman A , Eberhardt R
Number in seed: 52
Number in full: 42197
Average length of the domain: 250.10 aa
Average identity of full alignment: 19 %
Average coverage of the sequence by the domain: 62.50 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 57096847 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 23.2 23.2
Trusted cut-off 23.2 23.2
Noise cut-off 23.1 23.1
Model length: 261
Family (HMM) version: 24
Download: download the raw HMM for this family

Species distribution

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Archea Archea Eukaryota Eukaryota
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This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the adjacent tab. More...

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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the CN_hydrolase domain has been found. There are 290 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein sequence.

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