Aminotransferases share certain mechanistic features with other pyridoxal-phosphate dependent enzymes, such as the covalent binding of the pyridoxal-phosphate group to a lysine residue. On the basis of sequence similarity,
these various enzymes can be grouped [1,2] into subfamilies. One of these,
called class-I, currently consists of the following enzymes:
Aspartate aminotransferase (AAT) (EC 18.104.22.168). AAT catalyzes the reversible
transfer of the amino group from L-aspartate to 2-oxoglutarate to form
oxaloacetate and L-glutamate. In eukaryotes, there are two AAT isozymes:
one is located in the mitochondrial matrix, the second is cytoplasmic. In
prokaryotes, only one form of AAT is found (gene aspC).
Tyrosine aminotransferase (EC 22.214.171.124) which catalyzes the first step in
tyrosine catabolism by reversibly transferring its amino group to 2-
oxoglutarate to form 4-hydroxyphenylpyruvate and L-glutamate.
Aromatic aminotransferase (EC 126.96.36.199) involved in the synthesis of Phe,
Tyr, Asp and Leu (gene tyrB).
1-aminocyclopropane-1-carboxylate synthase (EC 188.8.131.52) (ACC synthase)
from plants. ACC synthase catalyzes the first step in ethylene
Pseudomonas denitrificans cobC, which is involved in cobalamin
Yeast hypothetical protein YJL060w.
The sequence around the pyridoxal-phosphate attachment site of this class of
enzyme is sufficiently conserved to allow the creation of a specific pattern.
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