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2.1.1.5: betaine-homocysteine S-methyltransferase

This is an abbreviated version!
For detailed information about betaine-homocysteine S-methyltransferase, go to the full flat file.

Word Map on EC 2.1.1.5

Reaction

betaine
+
L-homocysteine
=
dimethylglycine
+
L-methionine

Synonyms

betaine homocysteine methyltransferase, betaine homocysteine methyltransferase-1, betaine homocysteine S-methyltransferase, betaine-homocysteine methyltransferase, betaine-homocysteine S-methyltransferase, betaine-homocysteine S-methyltransferase 2, betaine-homocysteine S-methyltransferase-2, betaine-homocysteine transmethylase, betaine:homocysteine methyltransferase, betaine:homocysteine S-methyltransferase, BHMT, BHMT-1, BHMT-2, BHMT1, BHMT2, methyltransferase, betaine-homocysteine

ECTree

     2 Transferases
         2.1 Transferring one-carbon groups
             2.1.1 Methyltransferases
                2.1.1.5 betaine-homocysteine S-methyltransferase

Engineering

Engineering on EC 2.1.1.5 - betaine-homocysteine S-methyltransferase

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PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
A66V
-
nonsynonymous SNP identified using 240 DNA samples from four ethnic groups
Arg16Cys
-
nonsynonymous SNP identified using 240 DNA samples from four ethnic groups, Km (mM): 0.0139 (betaine), 0.0076 (L-homocysteine)
Arg239Gln
-
nonsynonymous SNP identified using 240 DNA samples from four ethnic groups, Km (mM): 0.012 (betaine), 0.0158 (L-homocysteine)
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
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
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
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
C217A
-
the mutation reduces zinc binding by 95% while abrogating catalytic activity, the mutation has no effect on the fold increase of GST-BHMT proteolytic fragment in the absence of nutrients
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
Cys217Ala
-
complete loss of activity, reduction in zinc binding, identification of zinc binding motif
Cys299Ala
-
complete loss of activity, reduction in zinc binding, identification of zinc binding motif
Cys300Ala
-
complete loss of activity, reduction in zinc binding, identification of zinc binding motif
D26A
almost 3fold decrease in stimulation by K+
DELTA325-406
truncation mutatnt does not express well in Escherichia coli and is inactive
DELTA371-406
truncation mutant does not express well in Escherichia coli and is inactive
E159A
complete loss of activity
E159Q
complete loss of activity
E266A
near-normal catalytic activity
G199S
-
in vascular patients with hyperhomocysteinemia
G27S
no stimulation by K+
G28S
very small decrease in stimulation by K+
G742A
-
in an ongoing, multicenter, case-control study including women with a clinical diagnosis of abruption an association between the homozygous mutant form of BHMT (742G to A) polymorphism and an increased risk for placental abruption is shown
Gly199Ser
-
nonsynonymous SNP identified using 240 DNA samples from four ethnic groups, Km (mM): 0.0139 (betaine), 0.0206 (L-homocysteine)
H338A
normal or near-normal ability to bind zinc, 10% of the wild-type activity
N364A
normal or near-normal ability to bind zinc, near-normal catalytic activity
P362A
normal or near-normal ability to bind zinc, near-normal catalytic activity
P365A
normal or near-normal ability to bind zinc, near-normal catalytic activity
Pro197Ser
-
nonsynonymous SNP identified using 240 DNA samples from four ethnic groups, Km (mM): 0.0213 (betaine), 0.0216 (L-homocysteine)
R239Q
-
no significant association with the severity and extent of hyperhomocysteinemia
R346A
normal or near-normal ability to bind zinc, negligible activity, elution as dimer, aberrant crosslinking properties
R361A
normal or near-normal ability to bind zinc, near-normal catalytic activity
T218M
-
nonsynonymous SNP identified using 240 DNA samples from four ethnic groups
V155F
-
nonsynonymous SNP identified using 240 DNA samples from four ethnic groups
V237M
-
nonsynonymous SNP identified using 240 DNA samples from four ethnic groups
W352A
Y363A
normal or near-normal ability to bind zinc, near-normal catalytic activity
A119G
1.9fold reduced turnover-number for betaine and L-homocysteine, 1.6fold reduced KM-value for L-homocysteine, 1.1fold decrease in Km-value for betaine
C186A
1.8fold reduced turnover-number for betaine and L-homocysteine, 4.3fold reduced KM-value for L-homocysteine, 1.8fold increase in Km-value for betaine
C186S
2.3fold reduced turnover-number for betaine and L-homocysteine, 1.4fold reduced KM-value for L-homocysteine, 111.6fold decrease in Km-value for betaine
D26A
2.7fold reduced turnover-number for betaine and L-homocysteine, 1.7fold reduced KM-value for L-homocysteine, 3.5fold increase in Km-value for betaine
D26I
67fold reduced turnover-number for betaine and L-homocysteine, maximal velocity is 6.5fold lower than the wild-type value
E159G
60fold reduced turnover-number for betaine and L-homocysteine, maximal velocity is 61.2fold lower than the wild-type value
E159K
170fold reduced turnover-number for betaine and L-homocysteine, maximal velocity is 169.7fold lower than the wild-type value
E21A
2.3fold reduced turnover-number for betaine and L-homocysteine, 6fold reduced KM-value for L-homocysteine, 2.4fold reduced Km-value for betaine
E21K
1.6fold reduced turnover-number for betaine and L-homocysteine, 1.4fold reduced KM-value for L-homocysteine, 1.7fold reduced Km-value for betaine
F74A
1.9fold reduced turnover-number for betaine and L-homocysteine, 1.9fold reduced KM-value for L-homocysteine, 2.9fold increase in Km-value for betaine
R346A
-
shows alterations in the association state
T184G
2.4fold reduced turnover-number for betaine and L-homocysteine, 3.19fold reduced KM-value for L-homocysteine, 1.6fold increase in Km-value for betaine
T73G
3.1fold reduced turnover-number for betaine and L-homocysteine, 2.2fold reduced KM-value for L-homocysteine, 1.3fold reduced Km-value for betaine
W352A
-
shows alterations in the association state
Y363A
-
shows alterations in the association state
Y77A
14fold reduced turnover-number for betaine and L-homocysteine, maximal velocity is 13.7fold lower than the wild-type value
additional information