Editing Lycopene (section)

==Structure and physical properties==
Lycopene is a symmetrical [[terpene|tetraterpene]] because it consists entirely of carbon and hydrogen and is derived from eight [[isoprene]] subunits.<ref name=lpi/> Isolation procedures for lycopene were first reported in 1910, and the structure of the molecule was determined by 1931. In its natural, all-''trans'' form, the molecule is long and somewhat flat, constrained by its system of 11 conjugated double bonds. The extended conjugation is responsible for its deep red color.<ref name=lpi/>

Plants and photosynthetic bacteria produce all-''trans'' lycopene.<ref name=lpi/> When exposed to light or heat, lycopene can undergo [[isomerization]] to any of a number of ''cis''-isomers, which have a less linear shape. Isomers distinct stabilities, with highest stability: 5-cis ≥ all-trans ≥ 9-cis ≥ 13-cis > 15-cis > 7-cis > 11-cis: lowest.<ref>{{cite journal|doi=10.1016/S0166-1280(01)00424-9|title=An ab initio computational study on selected lycopene isomers|journal=Journal of Molecular Structure: Theochem|volume=571|issue=1–3|pages=27–37|year=2001|last1=Chasse|first1=Gregory A.|last2=Mak|first2=Melody L.|last3=Deretey|first3=Eugen|last4=Farkas|first4=Imre|last5=Torday|first5=Ladislaus L.|last6=Papp|first6=Julius G.|last7=Sarma|first7=Dittakavi S.R|last8=Agarwal|first8=Anita|last9=Chakravarthi|first9=Sujatha|last10=Agarwal|first10=Sanjiv|last11=Rao|first11=A.Venket|url=https://publicatio.bibl.u-szeged.hu/28647/1/Anabinitiocomputationalstudyonselectedlycopeneisomers1-s2.0-S0166128001004249-main.pdf }}</ref><ref>{{cite journal|doi=10.1016/S0166-1280(01)00413-4|title=Conformational potential energy surfaces of a Lycopene model|journal=Journal of Molecular Structure: Theochem|volume=571|issue=1–3|pages=7–26|year=2001|last1=Chasse|first1=Gregory A.|last2=Chasse|first2=Kenneth P. |last3=Kucsman|first3=Arpad|last4=Torday|first4=Ladislaus L.|last5=Papp|first5=Julius G.|url=https://publicatio.bibl.u-szeged.hu/28646/1/ConformationalpotentialenergysurfacesofaLycopenemodel1-s2.0-S0166128001004134-main.pdf }}</ref> In human blood, various ''cis''-isomers constitute more than 60% of the total lycopene concentration, but the biological effects of individual isomers have not been investigated.<ref>{{cite journal|pmid=16046737|year=2005|last1=Erdman Jr|first1=J. W.|title=How do nutritional and hormonal status modify the bioavailability, uptake, and distribution of various isomers of lycopene?|journal=The Journal of Nutrition|volume=135|issue=8|pages=2046S–7S|doi=10.1093/jn/135.8.2046s|doi-access=free}}</ref>

[[Image:Carotenoid synthetic pathway.svg|thumb|Lycopene is a key intermediate in the biosynthesis of many carotenoids.]]

Carotenoids like lycopene are found in [[photosynthesis|photosynthetic]] pigment-protein complexes in plants, photosynthetic bacteria, fungi, and algae.<ref name=lpi/> They are responsible for the bright orange–red colors of fruits and vegetables, perform various functions in photosynthesis, and protect photosynthetic organisms from excessive light damage. Lycopene is a key intermediate in the biosynthesis of carotenoids, such as [[beta-carotene]], and [[xanthophyll]]s.<ref>{{cite web| last=NDSU Agriculture | title=What Color is Your Food? |url=http://www.ag.ndsu.edu/pubs/yf/foods/fn595w.htm | access-date=10 May 2012}}</ref>

Dispersed lycopene molecules can be encapsulated into [[carbon nanotube]]s enhancing their [[optical properties of carbon nanotubes|optical properties]].<ref>{{cite journal
 |author       = Yanagi, Kazuhiro
 |title        = Light-Harvesting Function of β-Carotene Inside Carbon Nanotubes
 |journal      = Phys. Rev. B
 |volume       = 74
 |issue        = 15
 |page         = 155420
 |year         = 2006
 |url          = http://pubman.nims.go.jp/pubman/item/escidoc:1587358:2/component/escidoc:1597178/Prb155420.pdf
 |doi          = 10.1103/PhysRevB.74.155420
 |last2        = Iakoubovskii
 |first2       = Konstantin
 |last3        = Kazaoui
 |first3       = Said
 |last4        = Minami
 |first4       = Nobutsugu
 |last5        = Maniwa
 |first5       = Yutaka
 |last6        = Miyata
 |first6       = Yasumitsu
 |last7        = Kataura
 |first7       = Hiromichi
 |bibcode      = 2006PhRvB..74o5420Y
 |access-date  = 2019-02-12
 |archive-date = 2020-10-02
 |archive-url  = https://web.archive.org/web/20201002235524/http://pubman.nims.go.jp/pubman/item/escidoc:1587358:2/component/escidoc:1597178/Prb155420.pdf
 |url-status   = dead
}}</ref> Efficient energy transfer occurs between the encapsulated dye and nanotube—light is absorbed by the dye and without significant loss is transferred to the nanotube. Encapsulation increases chemical and thermal stability of lycopene molecules; it also allows their isolation and individual characterization.<ref>
{{cite journal
 |author=Saito, Yuika
 |title=Vibrational Analysis of Organic Molecules Encapsulated in Carbon Nanotubes by Tip-Enhanced Raman Spectroscopy
 |journal=Jpn. J. Appl. Phys.
 |volume=45 |pages=9286–9289
 |year=2006
 |doi=10.1143/JJAP.45.9286
 |bibcode=2006JaJAP..45.9286S
 |issue=12
 |last2=Yanagi
 |first2=Kazuhiro
 |last3=Hayazawa
 |first3=Norihiko
 |last4=Ishitobi
 |first4=Hidekazu
 |last5=Ono
 |first5=Atsushi
 |last6=Kataura
 |first6=Hiromichi
 |last7=Kawata
 |first7=Satoshi
|s2cid=122152101
 }}</ref>

===Biosynthesis===
The unconditioned biosynthesis of lycopene in eukaryotic plants and in prokaryotic cyanobacteria is similar, as are the enzymes involved.<ref name=lpi/> Synthesis begins with [[mevalonic acid]], which is converted into [[dimethylallyl pyrophosphate]].  This is then condensed with three molecules of [[isopentenyl pyrophosphate]] (an isomer of dimethylallyl pyrophosphate), to give the 20-carbon [[geranylgeranyl pyrophosphate]].  Two molecules of this product are then condensed in a tail-to-tail configuration to give the 40-carbon [[phytoene]], the first committed step in carotenoid biosynthesis.  Through several desaturation steps, phytoene is converted into lycopene.  The two terminal isoprene groups of lycopene can be cyclized to produce beta-carotene, which can then be transformed into a wide variety of xanthophylls.<ref name=lpi/>

===Staining and removal===
Lycopene is the [[pigment]] in tomato sauces that turns plastic cookware orange. It is insoluble in plain water, but it can be dissolved in organic solvents and oils. Because of its non-polarity, lycopene in food preparations will stain any sufficiently [[porosity|porous]] material, including most plastics. To remove this staining, the plastics may be soaked in a solution containing a small amount of chlorine bleach.<ref>{{cite news|url=http://www.huffingtonpost.com/chris-barnes/how-to-clean-tomato-sauce_b_1521201.html|title=How To Clean Tomato Sauce Stains From Plastic Storage Containers|author=Barnes, Chris|date=11 October 2011|work=The Huffington Post|access-date=29 May 2017}}</ref>
The bleach oxidizes the lycopene, thus rendering it colourless.