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Glucose oxidase (GOX) catalyzes the oxidation of β-D-glucose to D-glucono-δ-lactone with the simultaneous reduction of enzyme-bound flavin. GOX exists as a homodimer, with each subunit binding one FAD molecule. Crystal structures show that FAD binds in a deep pocket of the enzyme near the dimer interface.
The interface between the two monomers of a single dimer of an ACAD contains the FAD binding sites and has extensive bonding interactions. In contrast, the interface between the two dimers has fewer interactions. There are a total of 4 active sites within the tetramer, each of which contains a single FAD molecule and an acyl-CoA substrate ...
In this reaction, the substrate not only is oxidized but also loses a carbon dioxide molecule, and is attached to the CoA coenzyme.) glucose-6-phosphate dehydrogenase (involved in the pentose phosphate pathway, producing NADPH) glyceraldehyde-3-phosphate dehydrogenase (involved in glycolysis, uses NAD +) sorbitol dehydrogenase; TCA cycle examples:
This led to the discovery that the protein studied required not riboflavin but flavin mononucleotide to be catalytically active. [ 6 ] [ 7 ] Similar experiments with D -amino acid oxidase [ 8 ] led to the identification of flavin adenine dinucleotide (FAD) as a second form of flavin utilised by enzymes.
FAD is the hydrogen acceptor, yielding FADH2. [7] 2. Enoyl-CoA hydrase catalyzes the addition of water across the newly formed double bond to make an alcohol. [5] [6] 3. 3-hydroxyacyl-CoA dehydrogenase oxidizes the alcohol group to a ketone. [5] NADH is produced from NAD+. [6] 4.
The first is called a "prosthetic group", which consists of a coenzyme that is tightly (or even covalently) and permanently bound to a protein. [4] The second type of coenzymes are called "cosubstrates", and are transiently bound to the protein. Cosubstrates may be released from a protein at some point, and then rebind later.
Glucose oxidase enzyme powder from Aspergillus niger. GOx is a dimeric protein, the 3D structure of which has been elucidated. The active site where glucose binds is in a deep pocket. The enzyme, like many proteins that act outside of cells, is covered with carbohydrate chains. GOx is a glucose oxidising enzyme with a molecular weight of 160 kDa.
Mutations of the BCKDK gene, whose protein product controls the activity of the complex, may result in over-activation of the complex and excessive catabolism of the three amino acids. This leads to branched-chain keto acid dehydrogenase kinase deficiency , a rare disease first described in humans in 2012.