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19  structures 35  species 3  interactions 210  sequences 8  architectures

Family: Alliinase_C (PF04864)

Summary: Allinase

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This is the Wikipedia entry entitled "Alliinase". More...

Alliinase Edit Wikipedia article

alliin lyase
EC number
CAS number 9031-77-0
IntEnz IntEnz view
ExPASy NiceZyme view
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
Gene Ontology AmiGO / EGO
PDB 2hor EBI.jpg
crystal structure of alliinase from garlic- apo form
Symbol Alliinase_C
Pfam PF04864
Pfam clan CL0061
InterPro IPR006948
SCOP 1lk9
Alliinase EGF-like domain
PDB 2hor EBI.jpg
crystal structure of alliinase from garlic- apo form
Symbol EGF_alliinase
Pfam PF04863
Pfam clan CL0001
InterPro IPR006947
SCOP 1lk9

In enzymology, an alliin lyase (EC is an enzyme that catalyzes the chemical reaction

an S-alkyl-L-cysteine S-oxide \rightleftharpoons an alkyl sulfenate + 2-aminoacrylate

Hence, this enzyme has one substrate, S-alkyl-L-cysteine S-oxide, and two products, alkyl sulfenate and 2-aminoacrylate.

This enzyme belongs to the family of lyases, specifically the class of carbon-sulfur lyases. The systematic name of this enzyme class is S-alkyl-L-cysteine S-oxide alkyl-sulfenate-lyase (2-aminoacrylate-forming). Other names in common use include alliinase, cysteine sulfoxide lyase, alkylcysteine sulfoxide lyase, S-alkylcysteine sulfoxide lyase, L-cysteine sulfoxide lyase, S-alkyl-L-cysteine sulfoxide lyase, and alliin alkyl-sulfenate-lyase. It employs one cofactor, pyridoxal phosphate.

Many alliinases contain a novel N-terminal epidermal growth factor-like domain (EGF-like domain).[1]


These enzymes are found in plants of the genus Allium, such as garlic and onions. Alliinase is responsible for catalyzing chemical reactions that produce the volatile chemicals that give these foods their flavors, odors, and tear-inducing properties. Alliinases are part of the plant's defense against herbivores. Alliinase is normally sequestered within a plant cell, but, when the plant is damaged by a feeding animal, the alliinase is released to catalyze the production of the pungent chemicals. This tends to have a deterrent effect on the animal. The same reaction occurs when onion or garlic is cut with a knife in the kitchen.


In garlic, an alliinase enzyme acts on the chemical alliin converting it into allicin. The process involves two stages: elimination of 2-propenesulfenic acid from the amino acid unit (with α-aminoacrylic acid as a byproduct), and then condensation of two of the sulfenic acid molecules.

Reaction scheme for the conversion: cysteine → alliin → allicin

Alliin and related substrates found in nature are chiral at the sulfoxide position (usually having the S absolute configuration, and alliin itself was the first natural product found to have both carbon- and sulfur-centered stereochemistry.[2] However, the sulfenic acid intermediate is not chiral, and the final product's stereochemistry is not controlled.

There are a range of similar enzymes that can react with the cysteine-derived sulfoxides present in different species. In onions, an isomer of alliin, isoalliin, is converted to 1-propenesulfenic acid. A separate enzyme, the lachrymatory factor synthase or LFS, then converts this chemical to syn-propanethial-S-oxide, a potent lachrymator. The analogous butyl compound, syn-butanethial-S-oxide, is found in Allium siculum species.[3]

Structural studies

As of late 2007, 3 structures have been solved for this class of enzymes, using X-ray crystallography. The PDB accession codes are 1LK9, 2HOR, and 2HOX.


  1. ^ Kuettner EB, Hilgenfeld R, Weiss MS (November 2002). "The active principle of garlic at atomic resolution". J. Biol. Chem. 277 (48): 46402–7. doi:10.1074/jbc.M208669200. PMID 12235163. 
  2. ^ Block, Eric (2009). Garlic and Other Alliums: The Lore and the Science. Cambridge, Eng: Royal Society of Chemistry. pp. 100–106. ISBN 0-85404-190-7. 
  3. ^ Kubec R, Cody RB, Dane AJ, Musah RA, Schraml J, Vattekkatte A, Block E (2010). "Applications of Direct Analysis in Real Time−Mass Spectrometry (DART-MS) in Allium Chemistry. (Z)-Butanethial S-Oxide and 1-Butenyl Thiosulfinates and their S-(E)-1-Butenylcysteine S-Oxide Precursor from Allium siculum". Journal of Agricultural and Food Chemistry 58 (2): 1121–1128. doi:10.1021/jf903733e. PMID 20047275. 


  • Durbin RD and Uchytil TF (1971). "Purification and properties of alliin lyase from the fungus Penicillium corymbiferum". Biochim. Biophys. Acta — Enzymology 235 (3): 518–520. doi:10.1016/0005-2744(71)90293-2. 
  • Goryachenkova, E. V. (1952). "Фермент в чесноке, который формирует allycine (allyinase), белок с phosphopyridoxal" [Enzyme in garlic which forms allycine (allyinase), a protein with phosphopyridoxal]. Doklady Akademii Nauk SSSR (in Russian) 87: 457–460. 
  • Jacobsen JV, Yamaguchi M, Howard FD and Bernhard RA (1968). "Product inhibition of the cysteine sulfoxide lyase of tulbaghia violacea". Arch. Biochem. Biophys. 127: 252–258. doi:10.1016/0003-9861(68)90223-3. 

External links

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

Allinase Provide feedback

Allicin is a thiosulphinate that gives rise to dithiines, allyl sulphides and ajoenes, the three groups of active compounds in Allium species. Allicin is synthesised from sulfoxide cysteine derivatives by alliinase ( EC:, whose C-S lyase activity cleaves C(beta)-S(gamma) bonds. It is thought that this enzyme forms part of a primitive plant defence system.

Literature references

  1. Kuettner EB, Hilgenfeld R, Weiss MS; , J Biol Chem 2002;0:0-0.: The active principle of garlic at atomic resolution. PUBMED:12235163 EPMC:12235163

Internal database links

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR006948

Allicin is a thiosulphinate that gives rise to dithiines, allyl sulphides and ajoenes, the three groups of active compounds in Allium species. Allicin is synthesised from sulphoxide cysteine derivatives by alliinase, whose C-S lyase activity cleaves C(beta)-S(gamma) bonds. It is thought that this enzyme forms part of a primitive plant defence system [PUBMED:12235163].

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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Pfam Clan

This family is a member of clan PLP_aminotran (CL0061), which has the following description:

This superfamily contains a variety of PLP-dependent enzymes.

The clan contains the following 15 members:

Alliinase_C Aminotran_1_2 Aminotran_3 Aminotran_5 Aminotran_MocR Beta_elim_lyase Cys_Met_Meta_PP DegT_DnrJ_EryC1 GDC-P Met_gamma_lyase OKR_DC_1 Pyridoxal_deC SelA SepSecS SHMT


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Seed source: Pfam-B_4527 (release 7.6)
Previous IDs: none
Type: Domain
Author: Mifsud W
Number in seed: 10
Number in full: 210
Average length of the domain: 299.40 aa
Average identity of full alignment: 44 %
Average coverage of the sequence by the domain: 78.44 %

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HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 11927849 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 22.0 22.0
Trusted cut-off 22.0 22.0
Noise cut-off 21.9 21.9
Model length: 363
Family (HMM) version: 10
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Species distribution

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There are 3 interactions for this family. More...

EGF_alliinase Alliinase_C EGF_alliinase


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 Alliinase_C domain has been found. There are 19 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 seqence.

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