Glucose-1-phosphate adenylyl transferase

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Glucose-1-phosphate adenylyl transferase ( potato , Solanum tuberosum )

Existing structural data : 1YP2 , 1YP3 , 1YP4

Mass / length primary structure 449 amino acids
Secondary to quaternary structure Heterotetramer
Identifier
External IDs
Enzyme classification
EC, category 2.7.7.27 ,  nucleotidyl transferase
Response type Transfer of an AMP molecule
Substrate α-D-glucose-1-phosphate + ATP
Products ADP-glucose + PP i
Occurrence
Parent taxon Bacteria , plants , unicellular eukaryotes

Glucose-1-phosphate adenylyltransferase is the enzyme that the transfer of a molecule of adenosine monophosphate (AMP) on glucose-1-phosphate catalyzed . This is the first step in the biosynthesis of starch in the plastids of plants. The enzyme is also found in bacteria, where it takes part in glycogen biosynthesis.

Catalyzed reaction

α-D-glucose-1-phosphate + ATP ADP-glucose + PP i

From ATP, AMP is transferred to glucose-1-phosphate with elimination of pyrophosphate ; ADP-glucose is produced. This activates the glucose and, with cleavage of ADP, can be attached to a starch polysaccharide chain for starch synthesis , which is then lengthened by one molecule of glucose. The cleavage of ADP provides the energy required for this condensation reaction . The reactions described run parallel to those of glycogen biosynthesis , only that ATP is used to activate glucose (reaction product: ADP-glucose) while uridine triphosphate (UTP) fulfills the same purpose in glycogen synthesis (reaction product: UDP-glucose)

Glucose-1-phosphate adenylyl transferase belongs to the enzyme family of nucleotidyl transferases ; Transferases , which are used to transfer groups of nucleotides .

Enzyme structure

At the end of 2007 3 structures of this enzyme class were clarified. You have the PDB access codes PDB link | 1YP2, PDB link | 1YP3, and PDB link | 1YP4.

Individual evidence

  1. ↑ Search result UniProt EC 2.7.7.27 according to taxonomy
  2. ↑ Ghosh HP, Preiss J: Adenosine diphosphate glucose pyrophosphorylase. A regulatory enzyme in the biosynthesis of starch in spinach leaf chloroplasts . In: J. Biol. Chem. . 241, No. 19, 1966, pp. 4491-504. PMID 5922972 .
  3. ↑ Shen L and Preiss J: Biosynthesis of bacterial glycogen. I. Purification and properties of the adenosine diphosphoglucose pyrophosphorylase of Arthrobacter species NRRL B1973 . In: J. Biol. Chem. . 240, 1965, pp. 2334-2340.

Web links

Wikibooks: Biochemistry and Pathobiochemistry: Glycogen Synthesis  - Learning and Teaching Materials