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Search The CSA
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Catalytic Site Atlas

CSA LITERATURE entry for 1b6b

E.C. namearalkylamine N-acetyltransferase
SpeciesOvis aries (Sheep)
E.C. Number (IntEnz) 2.3.1.87
CSA Homologues of 1b6b1cjw,1ib1,1kuv,1kux,1kuy,1l0c,
CSA Entries With UniProtID Q29495
CSA Entries With EC Number 2.3.1.87
PDBe Entry 1b6b
PDBSum Entry 1b6b
MACiE Entry M0022

Literature Report

IntroductionConversion of serotonin to N-acetylserotonin (the precursor to the circadian neurohormone melatonin) is catalysed by Aralkylamine N-acetyltransferase (AANAT). Levels of AANAT (and levels of melatonin) are controlled by the proteolysis of AANAT.
MechansimAralkylamine N-acetyltransferase has two conserved active site histidines, HIS 120 and HIS122, which are not found in the N-acyltransferase. Of the two histidine residues, HIS 122 has been proposed to act as the catalytic residue. The proposed catalytic mechanism involves HIS 122 acting as a general base in substrate deprotonation, and the subsequent formation of a tetravalent intermediate. The conserved residue TYR 168 could serve as a general acid catalyst to protonate the thiolate anion of coenzyme A.
Reaction

Catalytic Sites for 1b6b

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
SerB9797macie:sideChain
LeuB111111macie:mainChainCarbonyl
HisB122122macie:sideChain
LeuB124124macie:mainChainAmide
TyrB168168macie:sideChain

Annotated By Reference To The Literature - Site 2 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
SerA9797macie:sideChain
LeuA111111macie:mainChainCarbonyl
HisA122122macie:sideChain
LeuA124124macie:mainChainAmide
TyrA168168macie:sideChain

Literature References

Notes:
Hickman AB
Melatonin biosynthesis: the structure of serotonin N-acetyltransferase at 2.5 A resolution suggests a catalytic mechanism.
Mol Cell 1999 3 23-32
PubMed: 10024876
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