{{Short description|Class of enzymes}} {{Lowercase title}} {{infobox enzyme | Name = β-Glucosidase | EC_number = 3.2.1.21 | CAS_number = 9001-22-3 | GO_code = 0008422 | image = Beta_glucosidase_3AHX.png | width = | caption = The structure of β-glucosidase A from bacterium ''Clostridium cellulovorans''.<ref name="pmid20682343 ">{{PDB|3AHX}}; {{cite journal | vauthors = Jeng WY, Wang NC, Lin MH, Lin CT, Liaw YC, Chang WJ, Liu CI, Liang PH, Wang AH | display-authors = 6 | title = Structural and functional analysis of three β-glucosidases from bacterium ''Clostridium cellulovorans'', fungus ''Trichoderma reesei'' and termite ''Neotermes koshunensis'' | journal = Journal of Structural Biology | volume = 173 | issue = 1 | pages = 46–56 | date = January 2011 | pmid = 20682343 | doi = 10.1016/j.jsb.2010.07.008 | url = http://ntur.lib.ntu.edu.tw/bitstream/246246/243418/-1/96.pdf }}; rendered via [http://pymol.sourceforge.net PyMOL].</ref> }}
'''β-Glucosidase''' ({{EnzExplorer|3.2.1.21}}; systematic name '''β-<small>D</small>-glucoside glucohydrolase''') is an enzyme that catalyses the following reaction:<ref name="isbn1-57259-931-6">{{cite book | last1 = Cox | first1 = Michael | last2 = Lehninger | first2 = Albert L | last3 = Nelson | first3 = David R. | name-list-style = vanc | title = Lehninger principles of biochemistry | publisher = Worth Publishers | location = New York | year = 2000 | pages = [https://archive.org/details/lehningerprincip01lehn/page/306 306–308] | isbn = 1-57259-931-6 | url = https://archive.org/details/lehningerprincip01lehn/page/306 }}</ref> : Hydrolysis of terminal, non-reducing β-<small>D</small>-glucosyl residues with release of β-<small>D</small>-glucose
== Structure == β-Glucosidase is composed of two polypeptide chains.<ref>{{cite book | vauthors = Chida N, Sato T | chapter = 2.8 Chiral Pool Synthesis: Chiral Pool Syntheses Starting from Carbohydrates | title = In Comprehensive Chirality | year = 2012 | pages = 207–239 | veditors = Yamamoto H, Carreira EM | doi = 10.1016/B978-0-08-095167-6.00203-2 |isbn=978-0-08-095168-3}}</ref> Each chain is made up of 438 amino acids and constitute a subunit of the enzyme.<ref>{{cite journal | vauthors = Dale MP, Kopfler WP, Chait I, Byers LD | title = β-Glucosidase: substrate, solvent, and viscosity variation as probes of the rate-limiting steps | journal = Biochemistry | volume = 25 | issue = 9 | pages = 2522–9 | date = May 1986 | pmid = 3087421 | doi = 10.1021/bi00357a036 | url = https://doi.org/10.1021/bi00357a036 | url-access = subscription }}</ref> Each of these subunits contains an active site. The active site has three potential components: the pocket, the cleft, and the tunnel.<ref name=":0">{{cite journal | vauthors = Davies G, Henrissat B | title = Structures and mechanisms of glycosyl hydrolases | journal = Structure | volume = 3 | issue = 9 | pages = 853–9 | date = September 1995 | pmid = 8535779 | doi = 10.1016/S0969-2126(01)00220-9 | doi-access = free }}</ref> The pocket structure is beneficial for recognition of monosaccharide like glucose. The cleft 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.<ref name=":0" />
== Function == The function of the enzyme is to perform hydrolysis of various glycosides and oligosaccharides. The most significant oligosaccharide β-glucosidase reacts with is cellulose. Cellulose is a polymer composed of β-1,4-linked glucosyl residues. β-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. β‑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.<ref>{{Cite web|date=2013-10-02|title=The "Ping-Pong" Mechanism|url=https://chem.libretexts.org/Bookshelves/Biological_Chemistry/Supplemental_Modules_(Biological_Chemistry)/Enzymes/Enzymatic_Kinetics/Ping-pong_mechanisms|access-date=2020-10-20|website=Chemistry LibreTexts|language=en}}</ref> In the case of β-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.<ref>{{Cite journal|last=Konar|first=Sukanya|date=June 2019|title=Probing the Effect of Glucose on the Activity and Stability of β-Glucosidase: An All-Atom Molecular Dynamics Simulation Investigation |url= |journal=ACS Omega|volume=4|issue=6|pages=11189−11196|doi=10.1021/acsomega.9b00509|doi-access=free|pmid=31460219|pmc=6648728}}</ref> Depending on what the enzyme is reacting with the end product will be one or two glucose molecules.
=== Humans === In humans, tissues within the liver, small intestine, spleen and kidney contain a cytosolic β-glucosidase (CBG) that hydrolyses various β-d-glycosides. This human enzyme shows significant activity towards many xenobiotics commonly found in the human diet including glycosides of phytoestrogens, flavonoids, simple phenolics and cyanogens and human CBG hydrolyses a broad range of dietary glucosides, possibly playing a critical role in xenobiotic metabolism.<ref>{{Cite journal |last1=Berrin |first1=Jean-Guy |last2=McLauchlan |first2=W. Russell |last3=Needs |first3=Paul |last4=Williamson |first4=Gary |last5=Puigserver |first5=Antoine |last6=Kroon |first6=Paul A. |last7=Juge |first7=Nathalie |date=January 2002 |title=Functional expression of human liver cytosolic beta-glucosidase in Pichia pastoris. Insights into its role in the metabolism of dietary glucosides |journal=European Journal of Biochemistry |volume=269 |issue=1 |pages=249–258 |doi=10.1046/j.0014-2956.2001.02641.x |issn=0014-2956 |pmid=11784319}}</ref>
Liposomal β-glucosidase (glucocerebrosidas), found in human lysosomes, plays an important role in the degradation of glycosphingolipids, breaking down glucosylceramide into ceramide and glucose.<ref>{{cite book |title=Pediatric Neurology Part III |vauthors=Mignot C, Gelot A, De Villemeur TB |date=2013-01-01 |publisher=Elsevier |isbn=9780444595652 |veditors=Dulac O, Lassonde H, Sarnat HB |series=Handbook of Clinical Neurology |volume=113 |pages=1709–15 |chapter=Gaucher disease |doi=10.1016/B978-0-444-59565-2.00040-X |pmid=23622393 |chapter-url=http://www.sciencedirect.com/science/article/pii/B978044459565200040X}}</ref> Gaucher's disease is characterised by an accumulation of glucosylceramide in bodily tissues due to a lack of, or impaired activity of liposomal β-glucosidase, leading to weakened bones, liver damage, and enlargement of the spleen and impairment to its normal function.<ref>{{cite journal |display-authors=6 |vauthors=Michelin K, Wajner A, Goulart L, Fachel AA, Pereira ML, de Mello AS, Souza FT, Pires RF, Giugliani R, Coelho JC |date=May 2004 |title=Biochemical study on β-glucosidase in individuals with Gaucher's disease and normal subjects |journal=Clinica Chimica Acta; International Journal of Clinical Chemistry |volume=343 |issue=1–2 |pages=145–53 |doi=10.1016/j.cccn.2004.01.010 |pmid=15115687}}</ref>
Beyond β-glucosidases expressed in human tissues, bacterial β-glucosidases are also found in human saliva and inside the intestine produced by the bacterial microbiota of the mouth and gastro-intestinal tract, with various implications to normal human health, drug and hormone metabolism, and involvement in certain diseases.<ref>{{Cite journal |last1=Teixeira Essenfelder |first1=Lucimari |last2=Gomes |first2=Anderson Albino |last3=Coimbra |first3=Jefferson Luis Meirelles |last4=Moreira |first4=Marcelo Alves |last5=Ferraz |first5=Sandra Maria |last6=Miquelluti |first6=David José |last7=Felippe da Silva |first7=Gustavo |last8=Magalhães |first8=Maria de Lourdes Borba |date=2021-07-01 |title=Salivary β-glucosidase as a direct factor influencing the occurrence of halitosis |journal=Biochemistry and Biophysics Reports |volume=26 |article-number=100965 |doi=10.1016/j.bbrep.2021.100965 |issn=2405-5808 |pmc=7941027 |pmid=33732903}}</ref><ref>{{Cite journal |last1=Gao |first1=Song |last2=Sun |first2=Rongjin |last3=Singh |first3=Rashim |last4=Yu So |first4=Sik |last5=Chan |first5=Clement T. Y. |last6=Savidge |first6=Tor |last7=Hu |first7=Ming |date=2022-10-01 |title=The role of gut microbial β-glucuronidase in drug disposition and development |journal=Drug Discovery Today |volume=27 |issue=10 |pages=103316 |doi=10.1016/j.drudis.2022.07.001 |issn=1359-6446 |pmc=9717552 |pmid=35820618}}</ref>
=== Bonnethead Shark === 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.<ref>{{Cite journal |last1=Leigh |first1=Samantha C. |last2=Papastamatiou |first2=Yannis P. |last3=German |first3=Donovan P. |date=September 12, 2018 |title=Seagrass digestion by a notorious 'carnivore' |journal=Proceedings of the Royal Society B: Biological Sciences |language=en |volume=285 |issue=1886 |article-number=20181583 |doi=10.1098/rspb.2018.1583 |issn=0962-8452 |pmc=6158537 |pmid=30185641}}</ref> However, recent studies of the shark's hindgut has found that it has a high activity level of β-glucosidase.<ref>{{Cite journal |last1=Jhaveri |first1=Parth |last2=Papastamatiou |first2=Yannis P. |last3=German |first3=Donovan P. |date=November 2015 |title=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 |url=https://linkinghub.elsevier.com/retrieve/pii/S1095643315002019 |journal=Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology |language=en |volume=189 |pages=76–83 |doi=10.1016/j.cbpa.2015.07.013 |pmid=26239220 |hdl=10023/9230 }}</ref> During the digestive process of the bonnethead shark, the acidic stomach weakens the cell walls of the seagrass and allows for β-glucosidase to enter the cell and digest the cellulose. The activity level is on par with the monkeyface eel. The monkeyface eel is a herbivore, meaning that the bonnethead is able to perform the same digestive activity as a herbivore. Therefore, the bonnethead shark is now classified as an omnivore.
=== Christmas Island Red Crab === 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 β-glucosidase as they are terrestrial herbivores. In the case of the Christmas Island red crab β-glucosidase not only produces glucose, but also removes cellobiose.<ref name=":1">{{cite journal | vauthors = Allardyce BJ, Linton SM, Saborowski R | title = The last piece in the cellulase puzzle: the characterisation of β-glucosidase from the herbivorous gecarcinid land crab ''Gecarcoidea natalis ''| journal = The Journal of Experimental Biology | volume = 213 | issue = Pt 17 | pages = 2950–7 | date = September 2010 | pmid = 20709923 | doi = 10.1242/jeb.041582 | hdl = 10536/DRO/DU:30031463| s2cid = 3521384 | url = https://jeb.biologists.org/content/213/17/2950 | doi-access = free | bibcode = 2010JExpB.213.2950A| hdl-access = free }}</ref> This is important as cellobiose is an inhibitor for a number of enzymes including endo-β-1,4-glucanase and cellobiohydrolase. β-Glucosidase is also capable of hydrolysis on small oligomers that are produced by other enzymes without the assistance of an intermediate enzyme.<ref name=":1" /> This in turn makes β-glucosidase a very efficient enzyme in not only the digestive tract of the Christmas Island red crab, but other crustaceans as well.
== Synonyms == Synonyms, derivatives, and related enzymes include '''gentiobiase''', '''cellobiase''', '''emulsin''',<ref>{{cite book|last1=Mann|first1=Frederick George|title=Practical Organic Chemistry|last2=Saunders|first2=Bernard Charles|date=1975|publisher=Longman|isbn=9788125013808|edition=4th|location=London|pages=509–517|name-list-style=vanc}}</ref> '''elaterase''', '''aryl-β-glucosidase''', '''β-<small>D</small>-glucosidase''', '''β-glucoside glucohydrolase''', '''arbutinase''', '''amygdalinase''', '''''p''-nitrophenyl β-glucosidase''', '''primeverosidase''', '''amygdalase''', '''linamarase''', '''salicilinase''', and '''β-1,6-glucosidase'''. __NOTOC__ {{infobox protein |Name=glucosidase, beta, acid 3 (cytosolic) |caption= |image= |width= |HGNCid=19069 |Symbol=GBA3 |AltSymbols= CBGL1, KLRP |EntrezGene=57733 |OMIM=606619 |RefSeq=NM_020973 |UniProt=Q9H227 |PDB= |ECnumber=3.2.1.21 |Chromosome=4 |Arm=p |Band=15.31 |LocusSupplementaryData= }}
== See also == * Amygdalin β-glucosidase * Cellulase, a suite of enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze cellulolysis (i.e. the hydrolysis of cellulose) * Glucosylceramidase, a related enzyme * Prunasin β-glucosidase * Vicianin β-glucosidase
== References == {{Reflist}}
== External links == * {{MeshName|beta-Glucosidase}} * GO-database listing [http://www.ebi.ac.uk/ego/DisplayGoTerm?id=GO:0016162&selected=GO:0004553&viz=graph 'GO:0016162 cellulose 1,4-beta-cellobiosidase activity'] * Risk Assessment Summary, CEPA 1999. [http://www.ec.gc.ca/subsnouvelles-newsubs/default.asp?lang=En&n=AFDD052F-1 ''Trichoderma reesei'' P59G] {{Sugar hydrolases}} {{Enzymes}} {{Portal bar|Biology|border=no}}
Category:Carbohydrate metabolism Category:EC 3.2.1 Category:Enzymes of known structure