Beta-glucosidase

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β-glucosidase
Beta glucosidase 3AHX.png
The structure of beta-glucosidase A from bacterium Clostridium cellulovorans.[1]
Identifiers
EC number3.2.1.21
CAS number9001-22-3
Databases
IntEnzIntEnz view
BRENDABRENDA entry
ExPASyNiceZyme view
KEGGKEGG entry
MetaCycmetabolic pathway
PRIAMprofile
PDB structuresRCSB PDB PDBe PDBsum
Gene OntologyAmiGO / QuickGO

Beta-glucosidase is an enzyme that catalyzes the hydrolysis of the glycosidic bonds to terminal non-reducing residues in beta-D-glucosides and oligosaccharides, with release of glucose.[2]

Structure[edit]

Beta-glucosidase is composed of two polypeptide chains. These two chains are chiral in nature meaning that the chains are asymmetric and not superimposable.[3] Each chain is made up of 438 amino acids and constitute a subunit of the enzyme.[4] Each of these subunits contain an active site. The active site serves as the location where an enzyme and substrate bind and an enzymatic reaction can occur. The active site has three potential components: the pocket, the cleft, and the tunnel.[5] The pocket structure is beneficial for recognition of monosaccharide like glucose. The cleft is allows for binding of sugars to form polysaccharides. The tunnel allows for the enzyme to attach to polysaccharide and then release product while still attached to the sugar.[5]

Function[edit]

The function of the enzyme is preform hydrolysis of various glycosides and oligosaccharides. The most significant oligosaccharide beta-glucosidase reacts with is cellulose. Cellulose is a polymer composed of beta-1,4-linked glucosyl residues. Beta-glucosidases, Cellulases (endoglucanases), cellobiosidases (exoglucanases) are required by a number of organisms to consume it. These enzymes are powerful tools for degradation of plant cell walls by pathogens and other organisms consuming plant biomass. Beta glucosidases are essential for many organisms to digest a variety of nutrients. This enzyme completes double-displacement reaction, meaning that the enzyme is changed to an intermediate form when the first substrate enters the active site, it then releases the product before another substrate binds, and reverts to its original form by the end of the reaction.[6] In the case of beta-glucosidase, two carboxylate residues of glucosides, cellobiose, cellotriose, cellotetraose are involved at the active site. The purpose of the reaction is to remove the residues from disaccharide cellobiose to produce glucose during the hydrolysis of biomass.[7] Depending on the what the enzyme is reacting with the end product will be one or two glucose molecules.

Humans[edit]

Humans are unable to digest cellulose of plants cells. This is because the enzyme is not present in the human stomach, as the optimal pH is 5.6, while the pH of a human's stomach is acidic (between 1.5 and 3.5).[8] However, humans do require beta-glucosidase, Lysosomal β-glucosidase, as it plays an important role in the degradation of glycosphingolipids. The enzyme will break down glucosylceramide into ceramide and glucose.[9] If an accumulation occurs this will lead to Gaucher disease. The buildup of fatty substances can lead to weakening bones, liver damage, and enlarging and imparing the function the spleen.[10]

Bonnethead Shark[edit]

Bonnethead sharks are found in tropical and subtropical water living in estuaries with muddy or sandy bottoms, rich with seagrass. They were once thought of as being solely carnivores. It was known that bonnethead did consume seagrass, but it was viewed as incidental and dismissed as not helping the benefitting the shark.[11] However, recent studies of the shark's hindgut has found that it has a high activity level of beta glucosidase.[12] During the digestive process of the bonnethead shark, the acidic stomach weakens the cell walls of the seagrass and allows for beta-glucosidase to enter the cell and digest the cellulose. The activity level is on par with the monkeyface eel. The monkeyface eel is an herbivore, meaning that the bonnethead is able to preform the same digestive activity has an organism that is an herbivore. Therefore, the bonnethead shark is now classified as an omnivore.

Christmas Island Red Crab[edit]

The Christmas Island red crab is a species of crab located solely in the Christmas Island of the Indian Ocean. Land crabs such as these possess multiple varieties of Beta-glucosidase as they are terrestrial herbivores. In the case of the Christmas Island red crab beta glucosidase not only produces glucose, but also removes cellobiose.[13] This is important as cellobiose is an inhibitor for a number of enzymes including endo-β-1,4-glucanase and cellobiohydrolase. Beta-glucosidase is also capable completeling [sic?] hydrolysis on small oligomers that are produced by other enzymes without the assistance of an intermediate enzyme.[13] This in turn makes beta glucosidase a very efficient enzyme in not only the digestive tract of the Christmas Island red crab, but other crustaceans as well.

Synonyms[edit]

Synonyms, derivatives, and related enzymes include gentiobiase, cellobiase, emulsin,[14] elaterase, aryl-beta-glucosidase, beta-D-glucosidase, beta-glucoside glucohydrolase, arbutinase, amygdalinase, p-nitrophenyl beta-glucosidase, primeverosidase, amygdalase, linamarase, salicilinase, and beta-1,6-glucosidase.

glucosidase, beta, acid 3 (cytosolic)
Identifiers
SymbolGBA3
Alt. symbolsCBGL1, KLRP
NCBI gene57733
HGNC19069
OMIM606619
RefSeqNM_020973
UniProtQ9H227
Other data
EC number3.2.1.21
LocusChr. 4 p15.31

See also[edit]

References[edit]

  1. ^ PDB: 3AHX​; Jeng WY, Wang NC, Lin MH, Lin CT, Liaw YC, Chang WJ, et al. (January 2011). "Structural and functional analysis of three β-glucosidases from bacterium Clostridium cellulovorans, fungus Trichoderma reesei and termite Neotermes koshunensis". Journal of Structural Biology. 173 (1): 46–56. doi:10.1016/j.jsb.2010.07.008. PMID 20682343.; rendered via PyMOL.
  2. ^ Cox M, Lehninger AL, Nelson DR (2000). Lehninger principles of biochemistry. New York: Worth Publishers. pp. 306–308. ISBN 1-57259-931-6.
  3. ^ Chida N, Sato T (2012). "2.8 Chiral Pool Synthesis: Chiral Pool Syntheses Starting from Carbohydrates". In Yamamoto H, Carreira EM (eds.). In Comprehensive Chirality. pp. 207–239. doi:10.1016/B978-0-08-095167-6.00203-2. ISBN 978-0-08-095168-3.
  4. ^ Dale MP, Kopfler WP, Chait I, Byers LD (May 1986). "Beta-glucosidase: substrate, solvent, and viscosity variation as probes of the rate-limiting steps". Biochemistry. 25 (9): 2522–9. doi:10.1021/bi00357a036. PMID 3087421.
  5. ^ a b Davies G, Henrissat B (September 1995). "Structures and mechanisms of glycosyl hydrolases". Structure. 3 (9): 853–9. doi:10.1016/S0969-2126(01)00220-9. PMID 8535779.
  6. ^ "The "Ping-Pong" Mechanism". Chemistry LibreTexts. 2013-10-02. Retrieved 2020-10-20.
  7. ^ Konar, Sukanya (June 2019). "Probing the Effect of Glucose on the Activity and Stability of β‐Glucosidase: An All-Atom Molecular Dynamics Simulation Investigation". ACS Omega. 4 (6): 11189−11196. doi:10.1021/acsomega.9b00509. PMC 6648728. PMID 31460219.
  8. ^ "Carbohydrates - Cellulose". chemistry.elmhurst.edu. Retrieved 2020-10-20.
  9. ^ Mignot C, Gelot A, De Villemeur TB (2013-01-01). Dulac O, Lassonde H, Sarnat HB (eds.). "Gaucher disease". Handbook of Clinical Neurology. Pediatric Neurology Part III. Elsevier. 113: 1709–15. doi:10.1016/B978-0-444-59565-2.00040-X. ISBN 9780444595652. PMID 23622393.
  10. ^ Michelin K, Wajner A, Goulart L, Fachel AA, Pereira ML, de Mello AS, et al. (May 2004). "Biochemical study on beta-glucosidase in individuals with Gaucher's disease and normal subjects". Clinica Chimica Acta; International Journal of Clinical Chemistry. 343 (1–2): 145–53. doi:10.1016/j.cccn.2004.01.010. PMID 15115687.
  11. ^ Leigh SC, Papastamatiou YP, German DP (September 2018). "Seagrass digestion by a notorious 'carnivore'". Proceedings. Biological Sciences. 285 (1886): 20181583. doi:10.1098/rspb.2018.1583. PMC 6158537. PMID 30185641.
  12. ^ Jhaveri P, Papastamatiou YP, German DP (November 2015). "Digestive enzyme activities in the guts of bonnethead sharks (Sphyrna tiburo) provide insight into their digestive strategy and evidence for microbial digestion in their hindguts". Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology. 189: 76–83. doi:10.1016/j.cbpa.2015.07.013. hdl:10023/9230. PMID 26239220. S2CID 32666130.
  13. ^ a b Allardyce BJ, Linton SM, Saborowski R (September 2010). "The last piece in the cellulase puzzle: the characterisation of beta-glucosidase from the herbivorous gecarcinid land crab Gecarcoidea natalis". The Journal of Experimental Biology. 213 (Pt 17): 2950–7. doi:10.1242/jeb.041582. PMID 20709923. S2CID 3521384.
  14. ^ Mann FG, Saunders BC (1975). Practical Organic Chemistry (4th ed.). London: Longman. pp. 509–517. ISBN 9788125013808. Retrieved 1 February 2016.

External links[edit]