Adenosylhomocysteinase

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Structures	Swiss-model
Domains	InterPro

S-Adenosylhomocysteine hydrolase
S-Adenosylhomocysteine hydrolase
	SAH hydrolase tetramer, Human
Identifiers
Symbol	AHCY
NCBI gene	191
HGNC	343
OMIM	180960
RefSeq	NM_000687
UniProt	P23526
Other data
EC number	3.3.1.1
Locus	Chr. 20 q11.22
Structures
Search for
Structures	Swiss-model
Domains	InterPro

Adenosylhomocysteinase (EC 3.3.1.1, S-adenosylhomocysteine synthase, S-adenosylhomocysteine hydrolase, adenosylhomocysteine hydrolase, S-adenosylhomocysteinase, SAHase, AdoHcyase) is an enzyme that converts S-adenosylhomocysteine to homocysteine and adenosine.^[1]^[2] This enzyme catalyses the following chemical reaction

S-adenosyl-L-homocysteine + H₂O ⇌ L-homocysteine + adenosine

The enzyme contains one tightly bound NAD⁺ per subunit. The mechanism involves dehydrogenative oxidation of the 3'-OH of the ribose. The resulting ketone is susceptible to α-deprotonation. The resulting carbanion eliminates thiolate. The a,b-unsaturated ketone is then hydrated, and the ketone is reduced by the NADH.

References[]

^ De La Haba G, Cantoni GL (March 1959). "The enzymatic synthesis of S-adenosyl-L-homocysteine from adenosine and homocysteine". The Journal of Biological Chemistry. 234 (3): 603–8. PMID 13641268.
^ Palmer JL, Abeles RH (February 1979). "The mechanism of action of S-adenosylhomocysteinase". The Journal of Biological Chemistry. 254 (4): 1217–26. PMID 762125.

External links[]

Adenosylhomocysteinase at the US National Library of Medicine Medical Subject Headings (MeSH)

[1] De La Haba G, Cantoni GL (March 1959). "The enzymatic synthesis of S-adenosyl-L-homocysteine from adenosine and homocysteine". The Journal of Biological Chemistry. 234 (3): 603–8. PMID 13641268.

[2] Palmer JL, Abeles RH (February 1979). "The mechanism of action of S-adenosylhomocysteinase". The Journal of Biological Chemistry. 254 (4): 1217–26. PMID 762125.

[1]

[2]

v t Hydrolases: ether bond (EC 3.3)
3.3.1	Adenosylhomocysteinase
3.3.2	Epoxide hydrolase Leukotriene-A4 hydrolase

v t Enzymes
Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Diffusion-limited enzyme Coenzyme Cofactor Enzyme catalysis
Regulation	Allosteric regulation Cooperativity Enzyme inhibitor Enzyme activator
Classification	EC number Enzyme superfamily Enzyme family List of enzymes
Kinetics	Enzyme kinetics Eadie–Hofstee diagram Hanes–Woolf plot Lineweaver–Burk plot Michaelis–Menten kinetics
Types	EC1 Oxidoreductases (list) EC2 Transferases (list) EC3 Hydrolases (list) EC4 Lyases (list) EC5 Isomerases (list) EC6 Ligases (list) EC7 Translocases (list)