Chemistry:Glucose oxidase
| Glucose oxidase | |||||||||
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 Structure of glucose oxidase dimer (dark and light blue) complexed with FAD (salmon) and glycans (aquamarine) from Penicillium amagasakiense.[1] | |||||||||
| Identifiers | |||||||||
| EC number | 1.1.3.4 | ||||||||
| CAS number | 9001-37-0 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
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-alpha-D-Glucose.svg)
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| Names | |
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| Other names
Oxidase, glucose
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| Properties | |
| (C6H10O5)n | |
| Molar mass | variable |
| Appearance | white or yellow powder |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
 verify (what is   ?)
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| Infobox references | |
The glucose oxidase enzyme (GOx or GOD) also known as notatin (EC number 1.1.3.4) is an oxidoreductase that catalyses the oxidation of glucose to hydrogen peroxide and D-glucono-δ-lactone. This enzyme is produced by certain species of fungi and insects and displays antibacterial activity when oxygen and glucose are present.[2]
Glucose oxidase is widely used for the determination of free glucose in body fluids (medical testing), in vegetal raw material, and in the food industry. It also has many applications in biotechnologies, typically enzyme assays for biochemistry including biosensors in nanotechnologies.[3][4] It was first isolated by Detlev Müller in 1928 from Aspergillus niger.[5]
Function
Several species of fungi and insects synthesize glucose oxidase, which produces hydrogen peroxide, which kills bacteria.[2]
Notatin, extracted from antibacterial cultures of Penicillium notatum, was originally named Penicillin A, but was renamed to avoid confusion with penicillin.[6] Notatin was shown to be identical to Penicillin B and glucose oxidase, enzymes extracted from other molds besides P. notatum;[7] it is now generally known as glucose oxidase.[8]
Early experiments showed that notatin exhibits in vitro antibacterial activity (in the presence of glucose) due to hydrogen peroxide formation.[6][9] In vivo tests showed that notatin was not effective in protecting rodents from Streptococcus haemolyticus, Staphylococcus aureus, or salmonella, and caused severe tissue damage at some doses.[9]
Glucose oxidase is also produced by the hypopharyngeal glands of honeybee workers and deposited into honey where it acts as a natural preservative. GOx at the surface of the honey reduces atmospheric O2 to hydrogen peroxide (H2O2), which acts as an antimicrobial barrier.[10]
Structure
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. It is a dimeric glycoprotein consisting of two subunits each weighing 80 kDa. Flavinadenine dinucleotide (FAD) in the active site is buried approximately 1.5 nm inside the protein shell and acts as the initial electron acceptor.[11]
Mechanism
At pH 7, glucose exists in solution in cyclic hemiacetal form as 63.6% β-D-glucopyranose and 36.4% α-D-glucopyranose, the proportion of linear and furanose form being negligible. The glucose oxidase binds specifically to β-D-glucopyranose and does not act on α-D-glucose. It oxidises all of the glucose in solution because the equilibrium between the α and β anomers is driven towards the β side as it is consumed in the reaction.[3]
Glucose oxidase catalyzes the oxidation of β-D-glucose into D-glucono-1,5-lactone, which then hydrolyzes into gluconic acid.
In order to work as a catalyst, GOx requires a coenzyme, flavin adenine dinucleotide (FAD). FAD is a common component in biological oxidation-reduction (redox) reactions. Redox reactions involve a gain or loss of electrons from a molecule. In the GOx-catalyzed redox reaction, FAD works as the initial electron acceptor and is reduced to FADH−.[12] Then FADH− is oxidized by the final electron acceptor, molecular oxygen (O2), which can do so because it has a higher reduction potential. O2 is then reduced to hydrogen peroxide (H2O2).
Applications
Glucose monitoring
Glucose oxidase is widely used coupled to peroxidase reaction that visualizes colorimetrically the formed H2O2, for the determination of free glucose in sera or blood plasma for diagnostics, using spectrometric assays manually or with automated procedures, and even point-of-use rapid assays.[3][8]
Similar assays allows the monitoring of glucose levels in fermentation, bioreactors, and to control glucose in vegetal raw material and food products.[citation needed] In the glucose oxidase assay, the glucose is first oxidized, catalyzed by glucose oxidase, to produce gluconate and hydrogen peroxide. The hydrogen peroxide is then oxidatively coupled with a chromogen to produce a colored compound which may be measured spectroscopically. For example, hydrogen peroxide together with 4 amino-antipyrene (4-AAP) and phenol in the presence of peroxidase yield a red quinoeimine dye that can be measured at 505 nm. The absorbance at 505 nm is proportional to concentration of glucose in the sample.
Enzymatic glucose biosensors use an electrode instead of O2 to take up the electrons needed to oxidize glucose and produce an electronic current in proportion to glucose concentration.[13] This is the technology behind the disposable glucose sensor strips used by diabetics to monitor serum glucose levels.[14]
Food preservation
In manufacturing, GOx is used as an additive thanks to its oxidizing effects: it prompts for stronger dough in baking, replacing oxidants such as bromate.[15] It is also used as a food preservative to help remove oxygen and glucose from food when packaged such as dry egg powder to prevent unwanted browning and undesired taste.[16]
Wound treatment
Wound care products, such as "Flaminal Hydro" make use of an alginate hydrogel containing glucose oxidase and other components as an oxidation agent.
Clinical trials
A nasal spray from a bag-on-valve device that mixes glucose oxidase with glucose has undergone clinical trials in 2016 for the prevention and treatment of the common cold.[17][18][19]
See also
References
- ↑ PDB: 1gpe; Goodsell D (May 2006). "Molecule of the Month: Glucose Oxidase". RCSB Protein Data Bank. doi:10.2210/rcsb_pdb/mom_2006_5. https://pdb101.rcsb.org/motm/77.
- ↑ 2.0 2.1 "Glucose oxidase: natural occurrence, function, properties and industrial applications". Applied Microbiology and Biotechnology 78 (6): 927–938. Apr 2008. doi:10.1007/s00253-008-1407-4. PMID 18330562.
- ↑ 3.0 3.1 3.2 "Glucose Oxidase Technical sheet". Interchim. http://www.interchim.fr/ft/1/12718A.pdf.[yes|permanent dead link|dead link}}]
- ↑ "Molecular Effects of Encapsulation of Glucose Oxidase Dimer by Graphene". RSC Advances 5 (18): 13570–8. 2015. doi:10.1039/C4RA16852F. Bibcode: 2015RSCAd...513570G.
- ↑ "Detlev Müller discovers glucose oxidase". https://tacomed.com/chapter-x-modern-glucose-measuring/detlev-muller-discovers-glucose-oxidase/.
- ↑ 6.0 6.1 "Notatin: an anti-bacterial glucose-aerodehydrogenase from Penicillium notatum Westling and Penicillium resticulosum sp. nov". The Biochemical Journal 39 (1): 24–36. 1945. doi:10.1042/bj0390024. PMID 16747849.
- ↑ "Specificity of glucose oxidase (notatin)". The Biochemical Journal 50 (3): 331–41. Jan 1952. doi:10.1042/bj0500331. PMID 14915954.
- ↑ 8.0 8.1 "Glucose Oxidase as an Analytical Reagent". Critical Reviews in Analytical Chemistry 25 (1): 1–42. 1995. doi:10.1080/10408349508050556. http://www.biosensing.net/EBLA/Corso/Lezione%2001/GOD.PDF.
- ↑ 9.0 9.1 "Some pharmacological and chemotherapeutic properties of notatin". British Journal of Pharmacology and Chemotherapy 1 (4): 225–233. Dec 1946. doi:10.1111/j.1476-5381.1946.tb00041.x. PMID 19108091.
- ↑ "Honeybee glucose oxidase--its expression in honeybee workers and comparative analyses of its content and H2O2-mediated antibacterial activity in natural honeys". Die Naturwissenschaften 101 (8): 661–670. Aug 2014. doi:10.1007/s00114-014-1205-z. PMID 24969731. Bibcode: 2014NW....101..661B.
- ↑ Mano, Nicolas (2019). "Engineering glucose oxidase for bioelectrochemical applications.". Bioelectrochemistry 128: 218–240.
- ↑ Sanner, Christoph (March 1991). "15N‐ and 13C‐NMR investigations of glucose oxidase from Aspergillus niger". European Journal of Biochemistry 196 (3): 663–672. doi:10.1111/j.1432-1033.1991.tb15863.x. PMID 2013289.
- ↑ "The birth of protein electrochemistry". Chemical Communications (Royal Society of Chemistry) 49 (95): 11130–11132. Dec 2013. doi:10.1039/C3CC46060F. PMID 24153438.
- ↑ "Ferrocene-mediated enzyme electrode for amperometric determination of glucose". Analytical Chemistry (American Chemical Society) 56 (4): 667–671. Apr 1984. doi:10.1021/ac00268a018. PMID 6721151.
- ↑ "Glucose oxidase: natural occurrence, function, properties and industrial applications". Applied Microbiology and Biotechnology 78 (6): 927–38. April 2008. doi:10.1007/s00253-008-1407-4. PMID 18330562.
- ↑ "Improvement Strategies, Cost Effective Production, and Potential Applications of Fungal Glucose Oxidase (GOD): Current Updates". Frontiers in Microbiology 8: 1032. 2017. doi:10.3389/fmicb.2017.01032. PMID 28659876.
- ↑ Clinical trial number NCT01883427 for "Nasal Spray With Glucose Oxidase Preventing Common Cold in Pre-school Children" at ClinicalTrials.gov
- ↑ Clinical trial number NCT01883440 for "Glucose Oxidase as Treatment Against Common Cold" at ClinicalTrials.gov
- ↑ Clinical trial number NCT01883453 for "A Nasal Spray With Glucose Oxidase as a Treatment of Common Cold" at ClinicalTrials.gov
External links
- "Glucose Oxidase: A much used and much loved enzyme in biosensors" at University of Paisley
- Glucose+Oxidase at the US National Library of Medicine Medical Subject Headings (MeSH)
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