EzCatDB: D00106

DB codeD00106
RLCP classification6.30.115020.5300
6.20.93000.5520
CATH domainDomain 13.30.470.10
Domain 23.20.10.10Catalytic domain
E.C.2.6.1.42
CSA1iyd

CATH domainRelated DB codes (homologues)
3.20.10.10D00105
3.30.470.10D00105

Enzyme Name
Swiss-protKEGG

P0AB80O15382
Protein nameBranched-chain-amino-acid aminotransferaseBranched-chain-amino-acid aminotransferase, mitochondrialbranched-chain-amino-acid transaminase
transaminase B
branched-chain amino acid aminotransferase
branched-chain amino acid-glutamate transaminase
branched-chain aminotransferase
L-branched chain amino acid aminotransferase
glutamate-branched-chain amino acid transaminase
SynonymsBCAT
EC 2.6.1.42
Transaminase B
BCAT(m)
EC 2.6.1.42
Placental protein 18
PP18

KEGG pathways
MAP codePathways
MAP00280Valine, leucine and isoleucine degradation
MAP00290Valine, leucine and isoleucine biosynthesis
MAP00770Pantothenate and CoA biosynthesis

Swiss-prot:Accession NumberP0AB80O15382
Entry nameILVE_ECOLIBCAT2_HUMAN
ActivityL-leucine + 2-oxoglutarate = 4-methyl-2- oxopentanoate + L-glutamate.,2-oxoglutaric acid + L-isoleucine = (S)-3- methyl-2-oxopentanoic acid + L-glutamic acid.,2-oxoglutaric acid + L-valine = 3-methyl-2- oxobutanoic acid + L-glutamic acid.L-leucine + 2-oxoglutarate = 4-methyl-2- oxopentanoate + L-glutamate.,2-oxoglutaric acid + L-isoleucine = (S)-3- methyl-2-oxopentanoic acid + L-glutamic acid.,2-oxoglutaric acid + L-valine = 3-methyl-2- oxobutanoic acid + L-glutamic acid.
SubunitHomohexamer.Homodimer.
Subcellular location
Isoform A: Mitochondrion.,Isoform B: Cytoplasm.
CofactorPyridoxal phosphate.Pyridoxal phosphate.


CofactorsSubstratesProductsintermediates
KEGG-idC00018C00123C00407C00183C00026C00233C03465C00141C00025



CompoundPyridoxal phosphateL-LeucineL-IsoleucineL-Valine2-Oxoglutarate4-Methyl-2-oxopentanoate3-Methyl-2-oxopentanoate3-Methyl-2-oxobutanoateL-GlutamateExternal aldimineQuinonoid intermediateKetimine intermediateCarbinolamine intermediate
Typearomatic ring (with nitrogen atoms),phosphate group/phosphate ionamino acidsamino acidsamino acidscarbohydrate,carboxyl groupcarbohydrate,carboxyl groupcarbohydrate,carboxyl groupcarbohydrate,carboxyl groupamino acids,carboxyl group



1a3gA01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1a3gB01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1a3gC01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1i1kA01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1i1kB01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1i1kC01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1i1lA01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1i1lB01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1i1lC01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1i1mA01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1i1mB01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1i1mC01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1iydA01UnboundUnboundUnboundUnboundAnalogue:GUAUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1iydB01UnboundUnboundUnboundUnboundAnalogue:GUAUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1iydC01UnboundUnboundUnboundUnboundAnalogue:GUAUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1iyeA01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1iyeB01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1iyeC01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1ekfA01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1ekfB01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1ekpA01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1ekpB01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1ekvA01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1ekvB01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1kt8A01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1kt8B01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1ktaA01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1ktaB01UnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1a3gA02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1a3gB02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1a3gC02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1i1kA02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1i1kB02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1i1kC02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1i1lA02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundIntermediate-analogue:PLP-2MLUnboundUnboundUnbound
1i1lB02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundIntermediate-analogue:PLP-2MLUnboundUnboundUnbound
1i1lC02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundIntermediate-analogue:PLP-2MLUnboundUnboundUnbound
1i1mA02Bound:PLPUnboundUnboundAnalogue:4MVUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1i1mB02Bound:PLPUnboundUnboundAnalogue:4MVUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1i1mC02Bound:PLPUnboundUnboundAnalogue:4MVUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1iydA02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1iydB02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1iydC02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1iyeA02Analogue:PGUUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundIntermediate-analogue:PGUUnboundUnbound
1iyeB02Analogue:PGUUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundIntermediate-analogue:PGUUnboundUnbound
1iyeC02Analogue:PGUUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundIntermediate-analogue:PGUUnboundUnbound
1ekfA02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1ekfB02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1ekpA02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1ekpB02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1ekvA02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundIntermediate-analogue:PLP-TRS
1ekvB02Bound:PLPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundIntermediate-analogue:PLP-TRS
1kt8A02Analogue:ILPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundIntermediate-bound:ILPUnbound
1kt8B02Analogue:ILPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundIntermediate-bound:ILPUnbound
1ktaA02Analogue:PMPUnboundUnboundUnboundAnalogue:KIVUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound
1ktaB02Analogue:PMPUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnboundUnbound

Active-site residues
resource
Swiss-prot
pdbCatalytic residuesCofactor-binding residues
1a3gA01

1a3gB01

1a3gC01

1i1kA01

1i1kB01

1i1kC01

1i1lA01

1i1lB01

1i1lC01

1i1mA01

1i1mB01

1i1mC01

1iydA01

1iydB01

1iydC01

1iyeA01

1iyeB01

1iyeC01

1ekfA01

1ekfB01

1ekpA01

1ekpB01

1ekvA01

1ekvB01

1kt8A01

1kt8B01

1ktaA01

1ktaB01

1a3gA02LYS  159;TYR  164
LYS  159(PLP binding)
1a3gB02LYS  159;TYR  164
LYS  159(PLP binding)
1a3gC02LYS  159;TYR  164
LYS  159(PLP binding)
1i1kA02LYS  159;TYR  164
LYS  159(PLP binding)
1i1kB02LYS  659;TYR  664
LYS  659(PLP binding)
1i1kC02LYS 1159;TYR 1164
LYS 1159(PLP binding)
1i1lA02LYS  159;TYR  164
LYS  159(PLP binding)
1i1lB02LYS  659;TYR  664
LYS  659(PLP binding)
1i1lC02LYS 1159;TYR 1164
LYS 1159(PLP binding)
1i1mA02LYS  159;TYR  164
LYS  159(PLP binding)
1i1mB02LYS  659;TYR  664
LYS  659(PLP binding)
1i1mC02LYS 1159;TYR 1164
LYS 1159(PLP binding)
1iydA02LYS  159;TYR  164
LYS  159(PLP binding)
1iydB02LYS  159;TYR  164
LYS  159(PLP binding)
1iydC02LYS  159;TYR  164
LYS  159(PLP binding)
1iyeA02LYS  159;TYR  164
LYS  159(PLP binding)
1iyeB02LYS  159;TYR  164
LYS  159(PLP binding)
1iyeC02LYS  159;TYR  164
LYS  159(PLP binding)
1ekfA02LYS  202;TYR  207
LYS  202(PLP binding)
1ekfB02LYS  202;TYR  207
LYS  202(PLP binding)
1ekpA02LYS  202;TYR  207
LYS  202(PLP binding)
1ekpB02LYS  202;TYR  207
LYS  202(PLP binding)
1ekvA02LYS  202;TYR  207
LYS  202(PLP binding)
1ekvB02LYS  202;TYR  207
LYS  202(PLP binding)
1kt8A02LYS  202;TYR  207
LYS  202(PLP binding)
1kt8B02LYS  702;TYR  707
LYS  702(PLP binding)
1ktaA02LYS  202;TYR  207
LYS  202(PLP binding)
1ktaB02LYS  702;TYR  707
LYS  702(PLP binding)

References for Catalytic Mechanism
ReferencesSectionsNo. of steps in catalysis
[5]p.111-112
[6]p.7459-7460
[9]p.11594-11599
[10]Scheme 2, Fig.7, p.3728-3730, p.3731-3733

references
[1]
PubMed ID2666406
JournalJ Biochem (Tokyo)
Year1989
Volume105
Pages671-2
AuthorsKamitori S, Odagaki Y, Inoue K, Kuramitsu S, Kagamiyama H, Matsuura Y, Higuchi T
TitleCrystallization and preliminary X-ray characterization of branched-chain amino acid aminotransferase from Escherichia coli.
[2]
CommentsX-RAY CRYSTALLOGRAPHY (2.5 ANGSTROMS)
Medline ID97306043
PubMed ID9163511
JournalJ Biochem (Tokyo)
Year1997
Volume121
Pages637-41
AuthorsOkada K, Hirotsu K, Sato M, Hayashi H, Kagamiyama H
TitleThree-dimensional structure of Escherichia coli branched-chain amino acid aminotransferase at 2.5 A resolution.
Related PDB1a3g
Related Swiss-protP0AB80
[3]
PubMed ID9914259
JournalCurr Opin Struct Biol
Year1998
Volume8
Pages759-69
AuthorsJansonius JN
TitleStructure, evolution and action of vitamin B6-dependent enzymes.
[4]
PubMed ID10989422
JournalMethods Enzymol
Year2000
Volume324
Pages103-13
AuthorsKagamiyama H, Hayashi H
TitleBranched-chain amino-acid aminotransferase of Escherichia coli.
[5]
CommentsX-ray crystallography
PubMed ID11264579
JournalActa Crystallogr D Biol Crystallogr
Year2001
Volume57
Pages506-15
AuthorsYennawar N, Dunbar J, Conway M, Hutson S, Farber G
TitleThe structure of human mitochondrial branched-chain aminotransferase.
Related PDB1ekf,1ekp,1ekv
[6]
PubMed ID11412098
JournalBiochemistry
Year2001
Volume40
Pages7453-63
AuthorsOkada K, Hirotsu K, Hayashi H, Kagamiyama H
TitleStructures of Escherichia coli branched-chain amino acid aminotransferase and its complexes with 4-methylvalerate and 2-methylleucine: induced fit and substrate recognition of the enzyme.
Related PDB1i1k,1i1l,1i1m
[7]
PubMed ID11642362
JournalProg Nucleic Acid Res Mol Biol
Year2001
Volume70
Pages175-206
AuthorsHutson S
TitleStructure and function of branched chain aminotransferases.
[8]
PubMed ID12119021
JournalBiochemistry
Year2002
Volume41
Pages9070-8
AuthorsConway ME, Yennawar N, Wallin R, Poole LB, Hutson SM
TitleIdentification of a peroxide-sensitive redox switch at the CXXC motif in the human mitochondrial branched chain aminotransferase.
[9]
PubMed ID12269802
JournalBiochemistry
Year2002
Volume41
Pages11592-601
AuthorsYennawar NH, Conway ME, Yennawar HP, Farber GK, Hutson SM
TitleCrystal structures of human mitochondrial branched chain aminotransferase reaction intermediates: ketimine and pyridoxamine phosphate forms.
Related PDB1kt8,1kta
[10]
PubMed ID12667063
JournalBiochemistry
Year2003
Volume42
Pages3725-33
AuthorsGoto M, Miyahara I, Hayashi H, Kagamiyama H, Hirotsu K
TitleCrystal structures of branched-chain amino acid aminotransferase complexed with glutamate and glutarate: true reaction intermediate and double substrate recognition of the enzyme.
Related PDB1iyd,1iye

comments
This enzyme belongs to Type-VI PLP-dependent enzyme (see [3] & [5]).
According to the literature [10], this enzyme catalyzes the following reactions.
(A) Formation of external aldimine (with amine group of the first substrate, Leucine).
(A1) The negative charges from phosphate group of PLP and alpha-carboxylate of the first substrate may deprotonate the nucleophile, the alpha-amino group of the substrate (see [10]).
(A2) The activated alpha-amino group of the first substrate makes a nucleophilic attack on the C4' atom of PLP (from the si-face side), forming a tetrahedral intermediate.
(A3) Probably, the lone pair of the substituted amino group makes another attack on the C4' atom of PLP (from the si-face side), releasing Lys159. This may facilitated by O3 atom of PLP and Tyr164, considering the structure (see [10]). (The O3 atom might act as a acid-base to transfer a proton from the amine group to sidechain of Lys159.)
(B) Isomerization (change in the position of double-bond).
(B1) Lys159 acts as a general base to deprotonate the alpha-proton of the substrate bound to PLP, forming the quinonoid intermediate. The activity of Lys159 must be modulated by Tyr164 & O3 atom of PLP.
(B2) Lys159 acts as a general acid to protonate the C4' atom of the intermediate, forming the ketimine intermediate.
(C) Schiff-base deforming (by hydration), releasing the first product, 2-oxo acid, and PMP.
(C1) Lys159 acts as a general base to activate a water (at the re-face side of cofactor).
(C2) The activated water molecule makes a nucleophilic attack on the C-alpha atom of the substrate (from the re-face side), forming a carbinolamine intermediate.
(C3) The lone pair of the new hydroxyl group makes a nucleophilic attack on the C4' atom, releasing the first product. This reaction may facilitated by Tyr164 and the O3 atom of PLP. (The O3 atom might act as a base to deprotonate the sidechain of Lys159, which in turn deprotonate the hydroxyl group. The O3 atom then acts as a acid to protonate to the leaving amino group of the intermediate.)
(D) Schiff-base forming (of PMP with carbonyl group of the second substrate, Oxoglutarate; by dehydration).
(E) Isomerization (change in the position of double-bond).
(F) Formation of internal aldimine, releasing the second product, Glutamate.

createdupdated
2004-03-182009-02-26


Copyright: Nozomi Nagano, JST & CBRC-AIST
Funded by PRESTO/Japan Science and Technology Corporation (JST) (December 2001 - November 2004)
Funded by Grant-in-Aid for Publication of Scientific Research Results/Japan Society for the Promotion of Science (JSPS) (April 2005 - March 2006)
Funded by Grant-in-Aid for Scientific Research (B)/Japan Society for the Promotion of Science (JSPS) (April 2005 - March 2008)
Funded by BIRD/Japan Science and Technology Corporation (JST) (September 2005 - September 2010)
Funded by BIRD/Japan Science and Technology Corporation (JST) (October 2007 - September 2010)
Funded by Grant-in-Aid for Publication of Scientific Research Results/Japan Society for the Promotion of Science (JSPS) (April 2011 - March 2012)

© Computational Biology Research Center, AIST, 2004 All Rights Reserved.