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Literature summary extracted from

  • Castro, C.; Millian, N.S.; Garrow, T.A.
    Liver betaine-homocysteine S-methyltransferase activity undergoes a redox switch at the active site zinc (2008), Arch. Biochem. Biophys., 472, 26-33.
    View publication on PubMedView publication on EuropePMC

Activating Compound

EC Number Activating Compound Comment Organism Structure
2.1.1.5 beta-mercaptoethanol using a redox-inert methyl acceptor, it is shown that BHMT requires a thiol reducing agent for activity. Short-term exposure of BHMT to reducing agent-free buffer inactivates the enzyme without causing any loss of its catalytic zinc. Activity can be completely restored by the re-addition of a thiol reducing agent Homo sapiens

Protein Variants

EC Number Protein Variants Comment Organism
2.1.1.5 C104A site-directed mutagenesis is used to investigate whether the loss of the DMSA-Asp activity of BHMT when in the absence of a reducing agent is due to the oxidation of an essential thiol within the protein. By individual mutation of each of the five Cys residues not involved in Zn binding to Ala, it is shown that the resulting mutants are as active as wild-type enzyme when in the presence of beta-mercaptoethanol with the DMSA-Asp assay Homo sapiens
2.1.1.5 C131A site-directed mutagenesis is used to investigate whether the loss of the DMSA-Asp activity of BHMT when in the absence of a reducing agent is due to the oxidation of an essential thiol within the protein. By individual mutation of each of the five Cys residues not involved in Zn binding to Ala, it is shown that the resulting mutants are as active as wild-type enzyme when in the presence of beta-mercaptoethanol with the DMSA-Asp assay Homo sapiens
2.1.1.5 C186A site-directed mutagenesis is used to investigate whether the loss of the DMSA-Asp activity of BHMT when in the absence of a reducing agent is due to the oxidation of an essential thiol within the protein. By individual mutation of each of the five Cys residues not involved in Zn binding to Ala, it is shown that the resulting mutants are as active as wild-type enzyme when in the presence of beta-mercaptoethanol with the DMSA-Asp assay Homo sapiens
2.1.1.5 C201A site-directed mutagenesis is used to investigate whether the loss of the DMSA-Asp activity of BHMT when in the absence of a reducing agent is due to the oxidation of an essential thiol within the protein. By individual mutation of each of the five Cys residues not involved in Zn binding to Ala, it is shown that the resulting mutants are as active as wild-type enzyme when in the presence of beta-mercaptoethanol with the DMSA-Asp assay Homo sapiens
2.1.1.5 C256A site-directed mutagenesis is used to investigate whether the loss of the DMSA-Asp activity of BHMT when in the absence of a reducing agent is due to the oxidation of an essential thiol within the protein. By individual mutation of each of the five Cys residues not involved in Zn binding to Ala, it is shown that the resulting mutants are as active as wild-type enzyme when in the presence of beta-mercaptoethanol with the DMSA-Asp assay Homo sapiens
2.1.1.5 additional information experiments using the glutamate-cysteine ligase modifier subunit knockout mice Gclm(-/-), which are severely impaired in glutathione synthesis, show that the DMSA-Asp dependent BHMT activity is 75% lower in Gclm(-/-) than Gclm(+/+) mice. The Bet-Hcy dependent BHMT activity is essentially identical between both groups. This results show that the loss of DMSA-Asp dependent activity in Gclm(-/-) is due to the lower level of free thiols in those livers Mus musculus

Inhibitors

EC Number Inhibitors Comment Organism Structure
2.1.1.5 L-Asp 10 mM Asp inhibits BHMT Homo sapiens

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
2.1.1.5 10
-
 L-Asp
-
 Homo sapiens

Metals/Ions

EC Number Metals/Ions Comment Organism Structure
2.1.1.5 Zn2+ wild-type enzyme contains catalytic active zinc which is bound by three thiolates and one hydroxyl group. Long-term exposure of BHMT to reducing agent-free buffer results in the slow, irreversible loss of its catalytic Zn and a corresponding loss of activity Homo sapiens

Organism

EC Number Organism UniProt Comment Textmining
2.1.1.5 Homo sapiens
-
-
-
2.1.1.5 Mus musculus
-
-
-

Purification (Commentary)

EC Number Purification (Comment) Organism
2.1.1.5 wild-type and mutant enzymes are overexpressed in Escherichia coli and purified using the ImpactTM T7 system Homo sapiens

Source Tissue

EC Number Source Tissue Comment Organism Textmining
2.1.1.5 liver
-
 Mus musculus
-

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
2.1.1.5 L-Asp + dimethylsulfonioacetate
-
 Mus musculus ?
-
 ?
2.1.1.5 L-Asp + dimethylsulfonioacetate using the non-physiological methyl donor dimethylsulfonioacetate an O-methylation of Asp is performed by BHMT, but only in the presence of beta-mercaptoethanol Homo sapiens ?
-
 ?
2.1.1.5 L-homocysteine + betaine
-
 Mus musculus L-methionine + dimethylglycine
-
 ?
2.1.1.5 L-homocysteine + betaine
-
 Homo sapiens L-methionine + dimethylglycine
-
 ?

Synonyms

EC Number Synonyms Comment Organism
2.1.1.5 betaine-homocysteine S-methyltransferase
-
 Mus musculus
2.1.1.5 betaine-homocysteine S-methyltransferase
-
 Homo sapiens
2.1.1.5 BHMT
-
 Homo sapiens