Chlorophyll c
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Chlorophyll c refers to forms of chlorophyll found in certain marine algae, including the photosynthetic Chromista (e.g. diatoms and brown algae) and dinoflagellates.{{cite web |last=Speer |first=B. R. |title=Photosynthetic Pigments |url=http://www.ucmp.berkeley.edu/glossary/gloss3/pigments.html |access-date=2 August 2014}}{{cite journal |vauthors=Dougherty RC, Strain HH, Svec WA, Uphaus RA, Katz JJ |title=The structure, properties, and distribution of chlorophyll c |journal=Journal of the American Chemical Society |volume=92 |issue=9 |pages=2826–33 |date=May 1970 |pmid=5439971 |doi=10.1021/ja00712a037|bibcode=1970JAChS..92.2826D }} These pigments are characterized by their unusual chemical structure, with a porphyrin as opposed to the chlorin (which has a reduced ring D) as the core; they also do not have an isoprenoid tail. Both these features stand out from the other chlorophylls commonly found in algae and plants.{{cite book|author1-link=Robert E. Blankenship |last=Blankenship |first=Robert E. |name-list-style=vanc |title=Molecular Mechanisms of Photosynthesis |date=February 2002 |publisher=Wiley-Blackwell}}
It has a blue-green color and is an accessory pigment, particularly significant in its absorption of light in the 447–520 nm wavelength region. Like chlorophyll a and chlorophyll b, it helps the organism gather light and passes a quanta of excitation energy through the light harvesting antennae to the photosynthetic reaction centre.
Chlorophyll c can be further divided into chlorophyll c1, chlorophyll c2, and chlorophyll c3,{{cite journal |vauthors=Fookes CJ, Jeffrey SW |title=The structure of chlorophyll c3, a novel marine photosynthetic pigment |journal=J. Chem. Soc., Chem. Commun. |date=1989 |issue=23 |pages=1827–28 |doi=10.1039/C39890001827}} plus at least eight other more recently found subtypes.{{cite journal |last1=Zapata |first1=Manuel |last2=Garrido |first2=José L. |last3=Jeffrey |first3=Shirley W. |name-list-style=vanc |title=Chlorophyll c Pigments: Current Status |journal=Chlorophylls and Bacteriochlorophylls: Advances in Photosynthesis and Respiration |year=2006 |volume=25 |pages=39–53 |doi=10.1007/1-4020-4516-6_3 |series=Advances in Photosynthesis and Respiration |isbn=978-1-4020-4515-8}}
Chlorophyll ''c''<sub>1</sub>
Chlorophyll c1 is a common form of chlorophyll c. It differs from chlorophyll c2 in its C8 group, having an ethyl group instead of vinyl group (C-C single bond instead of C=C double bond).
Its absorption maxima are around 444, 577, 626 nm and 447, 579, 629 nm in diethyl ether and acetone respectively.{{cite journal | vauthors = Fawley MW | title = A new form of chlorophyll C involved in light-harvesting | journal = Plant Physiology | volume = 91 | issue = 2 | pages = 727–32 | date = October 1989 | pmid = 16667093 | pmc = 1062062 | doi = 10.1104/pp.91.2.727 }}
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Chlorophyll ''c''<sub>2</sub>
Chlorophyll c2 is the most common form of chlorophyll c.{{cite journal| vauthors = Jeffrey SW |title=The Occurrence of Chlorophyll c1 and c2 in Algae|journal=Journal of Phycology|date=September 1976|volume=12|issue=3|pages=349–354|doi=10.1111/j.1529-8817.1976.tb02855.x|bibcode=1976JPcgy..12..349J |s2cid=83927313 }}
Its absorption maxima are around 447, 580, 627 nm and 450, 581, 629 nm in diethyl ether and acetone respectively.
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Chlorophyll ''c''<sub>3</sub>
Chlorophyll c3 is a form of chlorophyll c found in microalga Emiliania huxleyi, identified in 1989.
Its absorption maxima are around 452, 585, 625 nm and 452, 585, 627 nm in diethyl ether and acetone respectively.
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Biosynthesis
Chlorophyll c synthesis branches off early from the typical Chlorophyllide synthesis pathway, after divinylprotochlorophyllide (DV-PChlide) is formed. It has been established that DV-PChlide and MV-PChlide are processed directly by a 171 oxidase (CHLC, chlorophyll c synthase) into Chl c2 and Chl c1, respectively.{{Cite journal |last1=Jiang |first1=Yanyou |last2=Cao |first2=Tianjun |last3=Yang |first3=Yuqing |last4=Zhang |first4=Huan |last5=Zhang |first5=Jingyu |last6=Li |first6=Xiaobo |date=2023-10-06 |title=A chlorophyll c synthase widely co-opted by phytoplankton |url=https://www.science.org/doi/10.1126/science.adg7921 |journal=Science |volume=382 |issue=6666 |pages=92–98 |doi=10.1126/science.adg7921|pmid=37797009 |bibcode=2023Sci...382...92J }}
The 171 oxidtion was proposed to proceed by "hydroxylation of the 17-propionate reside at the 171-position and successive dehydration to the 17-acrylate residue."{{cite journal |last1=Xu |first1=M |last2=Kinoshita |first2=Y |last3=Matsubara |first3=S |last4=Tamiaki |first4=H |date=March 2016 |title=Synthesis of chlorophyll-c derivatives by modifying natural chlorophyll-a. |journal=Photosynthesis Research |volume=127 |issue=3 |pages=335–45 |bibcode=2016PhoRe.127..335X |doi=10.1007/s11120-015-0190-1 |pmid=26346903 |s2cid=254944200}}
An 8-vinyl reductase (elaborating on the promiscuous behavior of ferredoxin-type 3,8-divinyl chlorophyllide reductase) could also convert Chl c2 into Chl c1. The two steps could be swapped for the same effect.{{cite journal |last1=Ito |first1=Hisashi |last2=Tanaka |first2=Ayumi |title=Evolution of a New Chlorophyll Metabolic Pathway Driven by the Dynamic Changes in Enzyme Promiscuous Activity |journal=Plant and Cell Physiology |date=March 2014 |volume=55 |issue=3 |pages=593–603 |doi=10.1093/pcp/pct203 |pmid=24399236|hdl=2115/58225 |hdl-access=free }}
Structure
| class="wikitable" style="text-align:center;width:100%;" |
| style="width:33%;" | Chlorophyll c1
! style="width:33%;" | Chlorophyll c2 ! style="width:33%;" | Chlorophyll c3 |
|---|
| valign="top" |{{Chembox
| Name= | verifiedrevid = 429169129 | ImageFile = Chlorophyll c1.svg | ImageSize = | ImageFile1 = Chlorophyll-c1-3D-balls.png | ImageAlt1 = Chlorophyll c1 molecule | IUPACName = [(2E)-3-[14-Ethyl-21-(methoxycarbonyl)-4,8,13,18-tetramethyl-20-oxo-9-vinyl-3,4-didehydro-3-phorbinyl-κ2N23,N25]acrylato(2-)]magnesium | OtherNames = |Section1={{Chembox Identifiers | index1_label = c1 | index2_label = c2 | index3_label = c3 | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 11003-45-5 | CASNo1_Ref = {{cascite|correct|CAS}} | CASNo1 = 18901-56-9 | CASNo2_Ref = {{cascite|correct|CAS}} | CASNo2 = 27736-03-4 | CASNo3_Ref = {{cascite|correct|CAS}} | CASNo3 = 111308-93-1 | UNII_Ref = {{fdacite|correct|FDA}} | UNII= 1A9E276K41 | UNII1_Ref = {{fdacite|correct|FDA}} | UNII1= 008W2KH70E | UNII2_Ref = {{fdacite|correct|FDA}} | UNII2= 8GAP92KIWW | UNII3_Ref = {{fdacite|correct|FDA}} | UNII3= FMN10170B8 | PubChem = 25245630 | ChEBI = 38202 | ChemSpiderID = 21865345 | Beilstein = 5801077, 6996880 | SMILES = CCC1=C(C)/C2=C/c3c(C=C)c(C)c4\C=C5/N=C(C(\C=C\C(O)=O)=C/5C)C5=c6c(C(=O)C5C(=O)OC)c(C)c(=CC1=N\2)n6[Mg]n34 | SMILES1 = COC(=O)C9C(=O)c6c(C)c3n7c6c9c2c(C=CC(=O)O)c(C)c1cc5n8c(cc4n([Mg]78n12)c(c=3)c(CC)c4c)c(C=C)c5C | StdInChI = 1S/C35H32N4O5.Mg/c1-8-19-15(3)22-12-24-17(5)21(10-11-28(40)41)32(38-24)30-31(35(43)44-7)34(42)29-18(6)25(39-33(29)30)14-27-20(9-2)16(4)23(37-27)13-26(19)36-22;/h8,10-14,31H,1,9H2,2-7H3,(H3,36,37,38,39,40,41,42);/q;+2/p-2/b11-10+,22-12-,23-13-,24-12-,25-14-,26-13-,27-14-,32-30-; | StdInChIKey = DGNIJJSSARBJSH-QRKQXEOSSA-L }} |Section2={{Chembox Properties | C=35 | H=30 | O=5 | N=4 | Mg=1 | Appearance = | Density = | MeltingPt = | BoilingPt = | Solubility = }} |Section3={{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPt = }} }} | valign="top" |{{Chembox | Name= | verifiedrevid = 428811250 | ImageFile = Chlorophyll c2.svg | ImageSize = 200px | ImageFile1 = Chlorophyll-c2-3D-balls.png | ImageAlt1 = Chlorophyll c2 molecule | IUPACName = [(2E)-3-[21-(Methoxycarbonyl)-4,8,13,18-tetramethyl-20-oxo-9,14-divinyl-3,4-didehydro-3-phorbinyl-κ2N23,N25]acrylato(2-)]magnesium | OtherNames = |Section1={{Chembox Identifiers | CASNo_Ref = {{cascite|correct|??}} | CASNo = 27736-03-4 | PubChem = 16070018 | ChemSpiderID = 21865346 | ChEBI = 38203 | UNII = 8GAP92KIWW | Beilstein = 5801049 6996841 | InChI=1S/C35H30N4O5.Mg/c1-8-19-15(3)22-12-24-17(5)21(10-11-28(40)41)32(38-24)30-31(35(43)44-7)34(42)29-18(6)25(39-33(29)30)14-27-20(9-2)16(4)23(37-27)13-26(19)36-22;/h8-14,31H,1-2H2,3-7H3,(H3,36,37,38,39,40,41,42);/q;+2/p-2/b11-10+,22-12?,23-13?,24-12?,25-14?,26-13?,27-14?,32-30?; | InChIKey = QDRBYWCRXZZVLY-JUQUGTHISA-L | SMILES = CC1=C(C2=CC3=NC(=CC4=C(C5=C([N-]4)C(=C6C(=C(C(=N6)C=C1[N-]2)C)C=CC(=O)O)C(C5=O)C(=O)OC)C)C(=C3C)C=C)C=C.[Mg+2] | SMILES1 = COC(=O)C9C(=O)c6c(C)c3n7c6c9c2c(C=CC(=O)O)c(C)c1cc5n8c(cc4n([Mg]78n12)c(c=3)c(C=C)c4c)c(C=C)c5C }} |Section2={{Chembox Properties | C=35 | H=28 | O=5 | N=4 | Mg=1 | Appearance = | Density = | MeltingPt = | BoilingPt = | Solubility = }} |Section3={{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPt = }} }} | valign="top" |{{Chembox | Name= | ImageFile = Chlorophyll c3.svg | ImageSize = 200px | ImageFile1 = | ImageAlt1 = | IUPACName = | OtherNames = |Section1={{Chembox Identifiers | CASNo_Ref = {{cascite|correct|??}} | CASNo = 111308-93-1 | ChemSpiderID = 32699592 | PubChem = 71587417 | UNII = FMN10170B8 | InChI=1S/C36H30N4O7.Mg/c1-8-18-15(3)21-12-22-16(4)20(10-11-27(41)42)32(39-22)30-31(36(45)47-7)34(43)28-17(5)23(40-33(28)30)13-25-19(9-2)29(35(44)46-6)26(38-25)14-24(18)37-21;/h8-14,31,38,43H,1-2H2,3-7H3,(H,41,42);/q;+2/p-2/b11-10+,21-12?,25-13?,26-14?,32-30?;/t31-;/m1./s1 | InChIKey = CWLZENTWIZFJMW-XUGDHDJXSA-L | SMILES = CC1=C(C2=NC1=CC3=NC(=C4C(C(=C5C4=NC(=C5C)C=C6C(=C(C(=C2)N6)C(=O)OC)C=C)[O-])C(=O)OC)C(=C3C)C=CC(=O)[O-])C=C.[Mg+2] }} |Section2={{Chembox Properties | C=36 | H=28 | O=7 | N=4 | Mg=1 | Appearance = | Density = | MeltingPt = | BoilingPt = | Solubility = }} |Section3={{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPt = }} }} |