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Pyrimidine (PYR) binding domain of thiamine pyrophosphate (TPP)-dependent enzymes Thiamine pyrophosphate (TPP) family, pyrimidine (PYR) binding domain; found in many key metabolic enzymes which use TPP (also known as thiamine diphosphate) as a cofactor. TPP binds in the cleft formed by a PYR domain and a PP domain. The PYR domain, binds the aminopyrimidine ring of TPP, the PP domain binds the diphosphate residue. A polar interaction between the conserved glutamate of the PYR domain and the N1' of the TPP aminopyrimidine ring is shared by most TPP-dependent enzymes, and participates in the activation of TPP. The PYR and PP domains have a common fold, but do not share strong sequence conservation. The PP domain is not included in this group. Most TPP-dependent enzymes have the PYR and PP domains on the same subunit although these domains can be alternatively arranged in the primary structure. In the case of 2-oxoisovalerate dehydrogenase (2OXO), sulfopyruvate decarboxylase (ComDE), and the E1 component of human pyruvate dehydrogenase complex (E1- PDHc) the PYR and PP domains appear on different subunits. TPP-dependent enzymes are multisubunit proteins, the smallest catalytic unit being a dimer-of-active sites. For many of these enzymes the active sites lie between PP and PYR domains on different subunits. However, for the homodimeric enzymes 1-deoxy-D-xylulose 5-phosphate synthase (DXS) and Desulfovibrio africanus pyruvate:ferredoxin oxidoreductase (PFOR), each active site lies at the interface of the PYR and PP domains from the same subunit. |
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Jiyao W et al.(2023). "The conserved domain database in 2023.",