Glycerol-3-Phosphate Dehydrogenase

Template:STRUCTURE 2r4e Glycerol 3-Phosphate Dehydrogenase

Glycerol 3-phosphate dehydrogenase (GlpD) is a membrane bound enzyme in prokaryotes and in eukaryotes. Glycerol 3-Phosphate Dehydrogenase (GlpD) is an oxidoreductase enzyme which catalyzes the reduction in reaction of Dihydroxyacetone Phosphate to Glycerol 3-Phosphate. GlpD is involved in many cellular functions such as phospholipids biosynthesis, respiration and metabolism. The GlpD is a dimer consisting of two subunits which contain the Cap-Domain,the flavin adenine dinucleotide(FAD)-Domain and a ubiquinone analogue, MD.

StructureStructure

GlpD is a dimer that consists of two subunits; α and β. The GlpD structure also contains seven ligands; 1,3-Dihydroxyacetonephosphate (13P), β-Octylglucoside (βOG), 1,2-Ethanediol (EDO), Flavin-Adenine Dinucleotide (FAD), Imidazole (IMD), PO4 (Phosphate Ion) and N-(Tris(Hydroxymethyl)methyl)-3-Aminopropanesulfonic Acid (T3A). The active sites on GlpD are the Cap-Domain, FAD- Domain and a ubiquinone substrate analogue, menadione (MD).

The C-terminal consists of negatively charged residues that are opposite in orientation to the positively charged residues of the FAD-Domain in the phospholipid membrane.

The N-terminal FAD-Domain exists in each monomer subunit of GlpD and is embedded into the phospholipid membrane bilayer. Substrate binding occurs at this domain which causes a conformational change to the structure of the GlpD enzyme. The base of the enzyme has positivly charged regions capable of association with the negatively charged heads of the phospholipid membrane. <ref>PubMed:18296637</ref2>

FunctionFunction

GlpD functions in the intracellular membrane of E. coli and in the inner-mitochondrial membrane of eukaryotes. In E. Coli, GlpD catalyzes and reduces the reaction of dihydroxyacetone phosphate to glycerol 3-phosphate in the glycerol metabolism pathway. The binding of the substrate analogues and GlpD, a conformational change of the structure of the GlpD occurs.

Upon the oxidation of glycerol 3-phosphate, flavin adenine dinucleotide (FAD) reduces to FADH2, passing on electrons to Ubiquinone(UQ). UQ then reduces to UQH2 which allows for the transport of electrons into the respiratory pathway.

Glycerol 3-phosphate dehydrogenase (GlpD) is a membrane bound enzyme in prokaryotes and in eukaryotes. GlpD is involved in many cellular functions, some of which are phospholipids biosynthesis, respiration and metabolism. The authors believed that GlpD undergoes a conformational change upon complexing with analogue substrates, which are thought to catalyze glycerol 3-phosphate (G3P) dehydrogenation in two possible ways. The authors further researched and discovered more GlpD structures that are bound to Ubiquonone (Ub) analogues in order to link catalytic dehydrogenation to respiration and to gain insight on the mechanism involved in the transport of electrons into the respiratory pathway. It is also thought by the authors that the prokaryotic enzyme structural results can be applied to eukaryotic GlpD enzyme structural results, due to the conservation of greater than 45% of consensus protein sequences in almost all organisms.

ReferencesReferences

Glycerol 3-Phosphate Dehydrogenase

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