View source for Galactose

{{short description|Monosaccharide sugar}}
{{for|the EP by The Sweet Science|Galactose (EP)}}
{{Chembox
| Verifiedfields = changed
| Watchedfields  = changed
| Name           = {{sm|d}}-Galactose
| verifiedrevid  = 456367432
| ImageFile      = Galactose-3D-balls.png
| ImageClass     = bg-transparent
| ImageFileL1    = Beta-D-Galactopyranose.svg
| ImageClassL1   = skin-invert-image
| ImageCaptionL1 = [[Haworth projection]] of<br />β-{{sm|d}}-galactopyranose
| ImageSizeL1    = 
| ImageFileR1    = DGalactose Fischer.svg
| ImageClassR1   = skin-invert-image
| ImageCaptionR1 = [[Fischer projection]] of<br />{{sm|d}}-galactose
| ImageSizeR1    = 70 px
| IUPACName      = Galactose<br />''galacto''-Hexose<ref>{{cite web | url=https://iupac.qmul.ac.uk/2carb/app.html | title=Appendix }}</ref>
| SystematicName = (2''R'',3''S'',4''S'',5''R'',6)-2,3,4,5,6-Pentahydroxyhexanal
| OtherNames     = Brain sugar
| Section1       = {{Chembox Identifiers
| IUPHAR_ligand = 4646
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 388480
| ChEMBL_Ref = {{ebicite|changed|EBI}}
| ChEMBL = 300520
| KEGG_Ref = {{keggcite|changed|kegg}}
| KEGG = D04291
| InChI = 1/C6H12O6/c7-1-2-3(8)4(9)5(10)6(11)12-2/h2-11H,1H2/t2−,3+,4+,5−,6+/m1/s1
| InChIKey = WQZGKKKJIJFFOK-PHYPRBDBBU
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C6H12O6/c7-1-2-3(8)4(9)5(10)6(11)12-2/h2-11H,1H2/t2−,3+,4+,5−,6+/m1/s1
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = WQZGKKKJIJFFOK-PHYPRBDBSA-N
| Beilstein = 1724619
| CASNo_Ref = {{cascite|changed|CAS}}
| CASNo =  59-23-4
| PubChem = 439357
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII =  X2RN3Q8DNE
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 28061
| SMILES = O[C@H]1[C@@H](O)[C@H](O[C@H](O)[C@@H]1O)CO
| MeSHName = Galactose
  }}
| Section2       = {{Chembox Properties
| C=6|H=12|O=6
| Appearance = White solid<ref name=GESTIS>{{GESTIS|ZVG=100237}}</ref>
| Odor = Odorless<ref name=GESTIS/>
| Density = 1.5 g/cm<sup>3</sup><ref name=GESTIS/>
| MeltingPtC = 168-170
| MeltingPt_ref = <ref name=GESTIS/>
| BoilingPt =
| Solubility = 650 g/L (20 °C)<ref name=GESTIS/>
| MagSus = −103.00·10<sup>−6</sup> cm<sup>3</sup>/mol
  }}
| Section6       = {{Chembox Pharmacology
| ATCCode_prefix = V04
| ATCCode_suffix = CE01
| ATC_Supplemental = {{ATC|V08|DA02}} ([[microparticle]]s)
}}
| Section7       = {{Chembox Hazards
| NFPA-H = 1
| NFPA-F = 0
| NFPA-R = 0
| MainHazards =
| FlashPt =
| AutoignitionPt =
  }}
}}

'''Galactose''' ({{IPAc-en|g|ə|ˈ|l|æ|k|t|oʊ|s}}, ''[[wikt:galacto-|galacto-]]'' + ''[[wikt:-ose#Suffix 2|-ose]]'',  sometimes abbreviated '''Gal''', is a common [[monosaccharide]], i.e. a simple sugar.  It is classified as a reducing hexose, more specifically an [[aldohexose]].<ref name=Conte>{{cite journal |last1=Conte |first1=Federica |last2=Van Buuringen |first2=Nicole |last3=Voermans |first3=Nicol C. |last4=Lefeber |first4=Dirk J. |title=Galactose in human metabolism, glycosylation and congenital metabolic diseases: Time for a closer look |journal=Biochimica et Biophysica Acta (BBA) - General Subjects |date=2021 |volume=1865 |issue=8 |article-number=129898 |doi=10.1016/j.bbagen.2021.129898 |pmid=33878388 |hdl=2066/235637 |hdl-access=free }}</ref>  In terms of structure, it is a C-4 [[epimer]] of glucose. A white, water-soluble solid, it is about as [[sweetness|sweet]] as [[glucose]], and about 65% as sweet as [[sucrose]].<ref>{{cite book|url=https://books.google.com/books?id=db5QAwAAQBAJ&pg=PA264|title=Optimising Sweet Taste in Foods| vauthors = Spillane WJ |date=2006-07-17|publisher=Woodhead Publishing|isbn=978-1-84569-164-6|page=264|language=en}}</ref>

==Occurrence==
[[Galactan]] is a [[polymer]]ic form of galactose found in [[hemicellulose]], and forming the core of the galactans, a class of natural polymeric carbohydrates.<ref>{{Cite book |url= https://books.google.com/books?id=GDuy5zL6eRAC&pg=PA78 |title= The Antibodies |last1=Zanetti |first1=Maurizio |last2=Capra |first2=Donald J. | name-list-style = vanc |date=2003-09-02 |publisher=CRC Press |isbn=978-0-203-21651-4 | page=78 }}</ref>

D-Galactose is also known as brain sugar since it is a component of [[glycoprotein]]s (oligosaccharide-protein compounds) found in [[Nerve tissue|nerve]] tissue.<ref>{{Cite web |title=16.3 Important Hexoses {{!}} The Basics of General, Organic, and Biological Chemistry |url=https://courses.lumenlearning.com/suny-orgbiochemistry/chapter/important-hexoses/ |access-date=2022-05-06 |website=courses.lumenlearning.com}}</ref>
Galactofuranose occurs in bacteria, fungi and protozoa,<ref>{{cite journal | vauthors = Nassau PM, Martin SL, Brown RE, Weston A, Monsey D, McNeil MR, Duncan K | display-authors = 6 | title = Galactofuranose biosynthesis in Escherichia coli K-12: identification and cloning of UDP-galactopyranose mutase | journal = Journal of Bacteriology | volume = 178 | issue = 4 | pages = 1047–52 | date = February 1996 | pmid = 8576037 | pmc = 177764 | url = | doi=10.1128/jb.178.4.1047-1052.1996}}</ref><ref>{{cite journal | vauthors = Tefsen B, Ram AF, van Die I, Routier FH | title = Galactofuranose in eukaryotes: aspects of biosynthesis and functional impact | journal = Glycobiology | volume = 22 | issue = 4 | pages = 456–69 | date = April 2012 | pmid = 21940757 | doi = 10.1093/glycob/cwr144 | doi-access = free }}</ref> and is recognized by a putative chordate immune lectin [[intelectin]] through its exocyclic 1,2-diol. 
===Relationship to lactose===
Galactose, when combined with glucose (another monosaccharide) through a [[condensation reaction]], gives the disaccharide called lactose. The [[hydrolysis]] of lactose to glucose and galactose is [[catalyzed]] by the [[enzyme]]s [[lactase]] and [[beta-galactosidase|β-galactosidase]]. The latter is produced by the [[Lac operon|''lac'' operon]] in ''[[Escherichia coli]]''.<ref>{{Citation |last1=Sanganeria |first1=Tanisha |title=Genetics, Inducible Operon |date=2023 |url=https://www.ncbi.nlm.nih.gov/books/NBK564361/ |work=StatPearls |access-date=2023-10-24 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=33232031 |last2=Bordoni |first2=Bruno}}</ref>

In nature, lactose is found primarily in milk and milk products. Consequently, various food products made with dairy-derived ingredients can contain lactose.<ref>{{cite web |url=http://digestive.niddk.nih.gov/ddiseases/pubs/lactoseintolerance/ |title=Lactose Intolerance – National Digestive Diseases Information Clearinghouse |last=Staff <!-- Verified: No author provided on page. --> |work=digestive.niddk.nih.gov |date=June 2009 |access-date=January 11, 2014 |archive-url=https://web.archive.org/web/20111125192619/http://digestive.niddk.nih.gov/ddiseases/pubs/lactoseintolerance/ |archive-date=November 25, 2011 }}</ref> Galactose is [[metabolism|metabolised]] to glucose by the three principal enzymes in a mechanism known as the [[Leloir pathway]]. The enzymes are listed in the order of the metabolic pathway: [[galactokinase]] (GALK), [[galactose-1-phosphate uridyltransferase]] (GALT), and [[UDP-galactose 4′-epimerase]] (GALE).{{Citation needed|date=February 2021}}

In human [[lactation]], galactose is required in a 1 to 1 ratio with glucose to enable the [[mammary glands]] to synthesize and secrete lactose. In a study where women were fed a diet containing galactose, 69 ± 6% of glucose and 54 ± 4% of galactose in the lactose they produced were derived directly from [[Blood plasma|plasma]] glucose, while 7 ± 2% of the glucose and 12 ± 2% of the galactose in the lactose, were derived directly from plasma galactose. 25 ± 8% of the glucose and 35 ± 6% of the galactose was synthesized from smaller molecules in a process referred to in the paper as [[Gluconeogenesis|hexoneogenesis]]. This suggests that the synthesis of galactose is supplemented by direct uptake and of use of plasma galactose when present.<ref name=sunehag>{{cite journal | vauthors = Sunehag A, Tigas S, Haymond MW | title = Contribution of plasma galactose and glucose to milk lactose synthesis during galactose ingestion | journal = The Journal of Clinical Endocrinology and Metabolism | volume = 88 | issue = 1 | pages = 225–9 | date = January 2003 | pmid = 12519857 | doi = 10.1210/jc.2002-020768 | doi-access = free }}</ref>

==Structure and isomerism==
[[File:D-Galactose Haworth.svg|thumb|left|upright=1.1|Cyclic forms of galactose]]
[[File:Galactose Sessel-Konformation.png|none|thumb|upright=1.85|Chair conformation of D-galactopyranose]]
{{clear|left}}
Galactose exists in both open-chain and cyclic form. The open-chain form is an [[aldehyde]] (RCHO).

Four isomers are cyclic, two of them with a [[pyranose]] (six-membered) ring and two with a [[furanose]] (five-membered) ring. Each cyclic form can exist as two [[anomer]]s, named alpha and beta, since a new [[stereocenter]] is generated upon cyclization at the site of the carbonyl.<ref name="Ophardt, C. Galactose">{{Cite web |url=http://elmhcx9.elmhurst.edu/~chm/vchembook/543galactose.html |title=Ophardt, C. Galactose |access-date=2015-11-26 |archive-url=https://web.archive.org/web/20060908164848/http://elmhcx9.elmhurst.edu/~chm/vchembook/543galactose.html |archive-date=2006-09-08 }}</ref> In the pyranose form, the OH group on C-3 is axial.


==Metabolism==
{| class="toccolours collapsible collapsed" width="100%" style="text-align:left"
! Metabolism of common [[monosaccharide]]s and some biochemical reactions of glucose
|-
|[[File:Metabolism of common monosaccharides, and related reactions.png|none|thumb|upright=4]]
|}
[[File:Leloir pathway.png|thumb|upright=1.35|Galactose metabolism]]
Glucose is more stable than galactose and is less susceptible to the formation of nonspecific [[glycoconjugate]]s, molecules with at least one sugar attached to a protein or lipid. Many speculate that it is for this reason that a pathway for rapid conversion from galactose to glucose has been [[Conserved sequence|highly conserved]] among many species.<ref name=OMMBID72>{{cite book |chapter-url=https://ommbid.mhmedical.com/content.aspx?bookid=971&sectionid=62672411 |chapter-url-access=subscription |title=The Online Metabolic and Molecular Bases of Inherited Disease |chapter=Galactosemia |vauthors=Fridovich-Keil JL, Walter JH |veditors=Valle D, Beaudet AL, Vogelstein B, Kinzler KW, Antonarakis SE, Ballabio A, Gibson KM, Mitchell G |access-date=2018-06-25 |archive-date=2018-06-26 |archive-url=https://web.archive.org/web/20180626030220/https://ommbid.mhmedical.com/content.aspx?bookid=971&sectionid=62672411 }}<br />a 4 b 21 c 22 d 22</ref>

The main pathway of galactose metabolism is the [[Leloir pathway]]; humans and other species, however, have been noted to contain several alternate pathways, such as the [[De Ley Doudoroff Pathway]]. The Leloir pathway consists of the latter stage of a two-part process that converts β-D-galactose to [[Uridine diphosphate glucose|UDP-glucose]]. The initial stage is the conversion of β-D-galactose to α-D-galactose by the enzyme, [[galactose mutarotase|mutarotase]] (GALM). The Leloir pathway then carries out the conversion of α-D-galactose to UDP-glucose via three principal enzymes: Galactokinase (GALK) phosphorylates α-D-galactose to galactose-1-phosphate, or Gal-1-P; Galactose-1-phosphate uridyltransferase (GALT) transfers a UMP group from UDP-glucose to Gal-1-P to form UDP-galactose; and finally, UDP galactose-4'-epimerase (GALE) interconverts UDP-galactose and UDP-glucose, thereby completing the pathway.<ref name=Bosch07>{{cite journal | vauthors = Bosch AM | title = Classical galactosaemia revisited | journal = Journal of Inherited Metabolic Disease | volume = 29 | issue = 4 | pages = 516–25 | date = August 2006 | pmid = 16838075 | doi = 10.1007/s10545-006-0382-0 | s2cid = 16382462 }}<br /> a 517 b 516 c 519</ref>

The above mechanisms for galactose metabolism are necessary because the human body cannot directly use galactose for energy metabolism, and it must first go through one of these processes.<ref>{{Cite book|last1=Berg|first1=Jeremy M.|last2=Tymoczko|first2=John L.|last3=Stryer|first3=Lubert|date=2013|title=Stryer Biochemie|doi=10.1007/978-3-8274-2989-6|isbn=978-3-8274-2988-9}}</ref>

[[Galactosemia]] is an inability to properly break down galactose due to a genetically inherited mutation in one of the enzymes in the Leloir pathway. As a result, the consumption of even small quantities is harmful to galactosemics.<ref>{{cite journal|url=https://www.ncbi.nlm.nih.gov/books/NBK1518/|title=Classic Galactosemia and Clinical Variant Galactosemia| first = Gerard T | last = Berry | name-list-style = vanc |journal=Nih.gov|access-date=17 May 2015|publisher=University of Washington, Seattle|year=1993|pmid=20301691}}</ref>

==Sources==
Galactose is found in [[dairy product]]s, [[avocados]], [[sugar beet]]s, other [[natural gum|gum]]s and [[mucilage]]s. It is also [[Biosynthesis|synthesized]] by the body, where it forms part of [[glycolipid]]s and [[glycoprotein]]s in several [[Biological tissue|tissue]]s; and is a by-product from the [[Algae fuel|third-generation ethanol]] production process (from [[macroalgae]]).{{Citation needed|date=February 2021}}

==Clinical significance==
Chronic systemic exposure of [[mice]], [[rat]]s, and ''[[Drosophila]]'' to D-galactose causes the acceleration of [[senescence]] (aging). It has been reported that high dose exposure of D-galactose (120&nbsp;mg/kg) can cause reduced sperm concentration and sperm motility in rodents and has been extensively used as an aging model when administered subcutaneously.<ref>{{cite journal | vauthors = Pourmemar E, Majdi A, Haramshahi M, Talebi M, Karimi P, Sadigh-Eteghad S | title = Intranasal Cerebrolysin Attenuates Learning and Memory Impairments in D-galactose-Induced Senescence in Mice | journal = Experimental Gerontology | volume = 87 | issue = Pt A | pages = 16–22 | date = January 2017 | pmid = 27894939 | doi = 10.1016/j.exger.2016.11.011 | s2cid = 40793896 }}</ref><ref>{{cite journal | vauthors = Cui X, Zuo P, Zhang Q, Li X, Hu Y, Long J, Packer L, Liu J | title = Chronic systemic D-galactose exposure induces memory loss, neurodegeneration, and oxidative damage in mice: protective effects of R-alpha-lipoic acid | journal = Journal of Neuroscience Research | volume = 84 | issue = 3 | pages = 647–54 | date = August 2006 | pmid = 16710848 | doi = 10.1002/jnr.20899 | s2cid = 13641006 }}</ref><ref>{{cite journal | vauthors = Zhou YY, Ji XF, Fu JP, Zhu XJ, Li RH, Mu CK, Wang CL, Song WW | display-authors = 6 | title = Gene Transcriptional and Metabolic Profile Changes in Mimetic Aging Mice Induced by D-Galactose | journal = PLOS ONE | volume = 10 | issue = 7 | article-number = e0132088 | date = 2015-07-15 | pmid = 26176541 | pmc = 4503422 | doi = 10.1371/journal.pone.0132088 | bibcode = 2015PLoSO..1032088Z | doi-access = free }}</ref>
Two studies have suggested a possible link between galactose in milk and [[ovarian cancer]].<ref>{{cite journal | vauthors = Cramer DW | title = Lactase persistence and milk consumption as determinants of ovarian cancer risk | journal = American Journal of Epidemiology | volume = 130 | issue = 5 | pages = 904–10 | date = November 1989 | pmid = 2510499 | doi=10.1093/oxfordjournals.aje.a115423}}</ref><ref>{{cite journal | vauthors = Cramer DW, Harlow BL, Willett WC, Welch WR, Bell DA, Scully RE, Ng WG, Knapp RC | title = Galactose consumption and metabolism in relation to the risk of ovarian cancer | journal = Lancet | volume = 2 | issue = 8654 | pages = 66–71 | date = July 1989 | pmid = 2567871 | doi = 10.1016/S0140-6736(89)90313-9 | s2cid = 34304536 }}</ref>  Other studies show no correlation, even in the presence of defective galactose metabolism.<ref>{{cite journal | vauthors = Goodman MT, Wu AH, Tung KH, McDuffie K, Cramer DW, Wilkens LR, Terada K, Reichardt JK, Ng WG | display-authors = 6 | title = Association of galactose-1-phosphate uridyltransferase activity and N314D genotype with the risk of ovarian cancer | journal = American Journal of Epidemiology | volume = 156 | issue = 8 | pages = 693–701 | date = October 2002 | pmid = 12370157 | doi = 10.1093/aje/kwf104 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Fung WL, Risch H, McLaughlin J, Rosen B, Cole D, Vesprini D, Narod SA | title = The N314D polymorphism of galactose-1-phosphate uridyl transferase does not modify the risk of ovarian cancer | journal = Cancer Epidemiology, Biomarkers & Prevention | volume = 12 | issue = 7 | pages = 678–80 | date = July 2003 | pmid = 12869412 }}</ref>  More recently, pooled analysis done by the [[Harvard School of Public Health]] showed no specific correlation between lactose-containing foods and ovarian cancer, and showed statistically insignificant increases in risk for consumption of lactose at 30 g/day.<ref>{{cite journal | vauthors = Genkinger JM, Hunter DJ, Spiegelman D, Anderson KE, Arslan A, Beeson WL, Buring JE, Fraser GE, Freudenheim JL, Goldbohm RA, Hankinson SE, Jacobs DR, Koushik A, Lacey JV, Larsson SC, Leitzmann M, McCullough ML, Miller AB, Rodriguez C, Rohan TE, Schouten LJ, Shore R, Smit E, Wolk A, Zhang SM, Smith-Warner SA | display-authors = 6 | title = Dairy products and ovarian cancer: a pooled analysis of 12 cohort studies | journal = Cancer Epidemiology, Biomarkers & Prevention | volume = 15 | issue = 2 | pages = 364–72 | date = February 2006 | pmid = 16492930 | doi = 10.1158/1055-9965.EPI-05-0484 | doi-access =  }}</ref>  More research is necessary to ascertain possible risks.{{Citation needed|date=February 2021}}

Some ongoing studies suggest galactose may have a role in treatment of [[focal segmental glomerulosclerosis]] (a kidney disease resulting in kidney failure and proteinuria).<ref name="pmid19509024">{{cite journal | vauthors = De Smet E, Rioux JP, Ammann H, Déziel C, Quérin S | title = FSGS permeability factor-associated nephrotic syndrome: remission after oral galactose therapy | journal = Nephrology, Dialysis, Transplantation | volume = 24 | issue = 9 | pages = 2938–40 | date = September 2009 | pmid = 19509024 | doi = 10.1093/ndt/gfp278 | doi-access = free }}</ref> This effect is likely to be a result of binding of galactose to FSGS factor.<ref>{{cite journal | vauthors = McCarthy ET, Sharma M, Savin VJ | title = Circulating permeability factors in idiopathic nephrotic syndrome and focal segmental glomerulosclerosis | journal = Clinical Journal of the American Society of Nephrology | volume = 5 | issue = 11 | pages = 2115–21 | date = November 2010 | pmid = 20966123 | doi = 10.2215/CJN.03800609 | doi-access = free }}</ref>

Galactose is a component of the [[antigen]]s (chemical markers) present on blood cells that distinguish blood type within the [[ABO blood group system]]. In O and A antigens, there are two [[monomer]]s of galactose on the antigens, whereas in the B antigens there are three monomers of galactose.<ref name="Raven and Johnson">{{cite book|title=Understanding Biology|edition=3rd| first1 = Peter H. | last1 = Raven | first2 = George B. | last2 = Johnson |page=203 |isbn=978-0-697-22213-8 |year=1995 | veditors = Mills CJ |publisher = WM C. Brown}}</ref>

A disaccharide composed of two units of galactose, [[galactose-alpha-1,3-galactose]] (alpha-gal), has been recognized as a potential [[allergen]] present in [[mammal meat]]. [[Alpha-gal allergy]] may be triggered by [[lone star tick]] bites.<ref>{{Cite web|title=Alpha-gal syndrome - Symptoms and causes|url=https://www.mayoclinic.org/diseases-conditions/alpha-gal-syndrome/symptoms-causes/syc-20428608|access-date=2022-02-25|website=Mayo Clinic|language=en}}</ref>

Galactose in sodium saccharin solution has also been found to cause conditioned flavor avoidance in adult female rats within a laboratory setting when combined with intragastric injections.<ref name=":0">{{Cite journal|last1=Sclafani|first1=Anthony|last2=Fanizza|first2=Lawrence J|last3=Azzara|first3=Anthony V|date=1999-08-15|title=Conditioned Flavor Avoidance, Preference, and Indifference Produced by Intragastric Infusions of Galactose, Glucose, and Fructose in Rats|url=https://www.sciencedirect.com/science/article/pii/S0031938499000530|journal=Physiology & Behavior|language=en|volume=67|issue=2|pages=227–234|doi=10.1016/S0031-9384(99)00053-0|pmid=10477054|s2cid=37225025|issn=0031-9384|url-access=subscription}}</ref> The reason for this flavor avoidance is still unknown. However, a decrease in the levels of the enzymes required to convert galactose to glucose in the liver of the rats could be responsible.<ref name=":0" />

== History ==

In 1855, E. O. Erdmann noted that hydrolysis of lactose produced a substance besides glucose.<ref>{{cite thesis | first = Eduard Otto | last = Erdmann | name-list-style = vanc | date = 1855 | title = Dissertatio de saccharo lactico et amylaceo | trans-title = Dissertation on milk sugar and starch | language = la | publisher = University of Berlin }}</ref><ref>{{cite web | title = Jahresbericht über die Fortschritte der reinen, pharmaceutischen und technischen Chemie | trans-title = Annual report on progress in pure, pharmaceutical, and technical chemistry | language = de | date = 1855 | url = https://books.google.com/books?id=7LVZAAAAcAAJ&pg=PA671 | pages = 671–673 }} see especially p. 673.</ref>

Galactose was first isolated and studied by [[Louis Pasteur]] in 1856 and he called it "lactose".<ref>{{cite journal | vauthors = Pasteur L | date = 1856 | url = https://archive.org/stream/ComptesRendusAcademieDesSciences0042/ComptesRendusAcadmieDesSciences-Tome042-Janvier-juin1856#page/n350/mode/1up | title = Note sur le sucre de lait | trans-title = Note on milk sugar | language = fr | journal = Comptes rendus | volume = 42 | pages =  347–351 | quote = From page 348: Je propose de le nommer ''lactose''. (I propose to name it ''lactose''.)}}</ref> In 1860, [[Marcellin Berthelot|Berthelot]] renamed it "galactose" or "glucose lactique".<ref>{{cite journal | first = Marcellin | last = Berthelot | name-list-style = vanc | title = Chimie organique fondée sur la synthèse | trans-title = Organic chemistry based on synthesis | language = fr | location = Paris, France | journal = Mallet-Bachelier | date = 1860 | volume = 2 | pages = 248–249 | url = https://books.google.com/books?id=7AtQYV5FlVwC&pg=PA248 }}</ref><ref>"Galactose" — from the [[Ancient Greek]] [[wikt:γάλακτος|γάλακτος]] (gálaktos, "milk").</ref> In 1894, [[Hermann Emil Fischer|Emil Fischer]] and Robert Morrell determined the [[molecular configuration|configuration]] of galactose.<ref>{{cite journal | first1 = Emil | last1 = Fischer | first2 = Robert S. | last2 = Morrell | name-list-style = vanc | date = 1894 | url = http://gallica.bnf.fr/ark:/12148/bpt6k90732c/f403.image.langEN | title = Ueber die Configuration der Rhamnose und Galactose | trans-title = On the configuration of rhamnose and galactose | language = de | journal = Berichte der Deutschen Chemischen Gesellschaft zu Berlin | volume = 27 | pages = 382–394 | doi=10.1002/cber.18940270177}} The configuration of galactose appears on page 385.</ref>

==Etymology==
The word ''galactose'' is derived from [[Greek language|Greek]] {{wikt-lang|el|γάλακτος}}, {{translit|grc|galaktos}} {{gloss|of milk}}, and the generic chemical suffix for sugars ''[[-ose]]''.<ref name=Conte/> The etymology is comparable to that of the word ''[[lactose]]'' in that both contain roots meaning "milk sugar".

==Spectroscopy==
The [[Infrared spectroscopy|IR spectra]] for galactose shows a broad, strong stretch from roughly wavenumber 2500&nbsp;cm<sup>−1</sup> to wavenumber 3700&nbsp;cm<sup>−1</sup>.<ref name=":1">{{Cite journal|last1=Tunki|first1=Lakshmi|last2=Kulhari|first2=Hitesh|last3=Vadithe|first3=Lakshma Nayak|last4=Kuncha|first4=Madhusudana|last5=Bhargava|first5=Suresh|last6=Pooja|first6=Deep|last7=Sistla|first7=Ramakrishna|date=2019-09-01|title=Modulating the site-specific oral delivery of sorafenib using sugar-grafted nanoparticles for hepatocellular carcinoma treatment|journal=European Journal of Pharmaceutical Sciences|language=en|volume=137|article-number=104978|doi=10.1016/j.ejps.2019.104978|pmid=31254645|s2cid=195764874|issn=0928-0987|doi-access=free}}</ref>

The [[Proton nuclear magnetic resonance|Proton NMR]] spectra for galactose includes peaks at 4.7 ppm (D<sub>2</sub>O), 4.15 ppm (−CH<sub>2</sub>OH), 3.75, 3.61, 3.48 and 3.20 ppm (−CH<sub>2</sub> of ring), 2.79–1.90 ppm (−OH).<ref name=":1" />

==Further reading==
*{{cite book|last1=Bhat|first1=Paike Jayadeva | name-list-style = vanc |title=Galactose Regulon of Yeast: From Genetics to Systems Biology |url=https://books.google.com/books?id=ofEx-CsVlIAC&q=galactose+is+coined+by&pg=PA127|publisher=Springer Science & Business Media|access-date=26 December 2017|language=en|date=2 March 2008|isbn=978-3-540-74015-5}}
It is a white, water soluble solid.

== See also ==
* [[Galactogen]]
* [[Galactolysis]]

== References ==
{{Reflist}}

== External links ==
* {{Commons category-inline}}

{{Sugar}}
{{Carbohydrates}}

[[Category:Galactose| ]]
[[Category:Nutrition]]
[[Category:Pyranoses]]
[[Category:Furanoses]]