bacteriochlorophyll bacteriochlorophyll bacteriochlorophylls (bchl) are photosynthetic pigments that occur in various phototrophic bacteria. they were discovered by c. b. van niel in 1932. they are related to chlorophylls, which are the primary pigments in plants, algae, and cyanobacteria. organisms that contain bacteriochlorophyll conduct photosynthesis to sustain their energy requirements, but do not produce oxygen as a byproduct. they use wavelengths of light not absorbed by plants or cyanobacteria. replacement of mg2+ with protons gives bacteriophaeophytin (bph), the phaeophytin form. list of major bacteriochlorophylls pigment taxa in vivo infrared absorption maximum (nm) bchl a purple bacteria, heliobacteria, green sulfur bacteria, chloroflexota, chloracidobacterium thermophilum 805, 830–890 bchl b purple bacteria 835–850, 1020–1040 bchl c green sulfur bacteria, chloroflexota, c. thermophilum 745–755 bchl d green sulfur bacteria 705–740 bchl e green sulfur bacteria 719–726 bchl f (discovered by mutation of bchl e synthesis by analogy to bchl c/d. not evolutionarily favorable.) 700–710 bchl g heliobacteria 670, 788 structures of major bacteriochlorophylls bacteriochlorophyll a bacteriochlorophyll b bacteriochlorophyll c bacteriochlorophyll d bacteriochlorophyll e bacteriochlorophyll f bacteriochlorophyll g bacteriochlorophyll a names iupac name oxy)propyl)-13,14-dihydrophorbine-21-carboxylatato(2−)-kappa4n23,n24,n25,n26]magnesium identifiers cas number 17499-98-8 y 3d model (jsmol) interactive image chebi chebi:30033 chemspider 21169457 y kegg c11242 pubchem cid 11953947 inchi inchi=1s/c55h75n4o6.mg/c1-13-39-34(7)41-29-46-48(38(11)60)36(9)43(57-46)27-42-35(8)40(52(58-42)50-51(55(63)64-12)54(62)49-37(10)44(59-53(49)50)28-45(39)56-41)23-24-47(61)65-26-25-33(6)22-16-21-32(5)20-15-19-31(4)18-14-17-30(2)3;/h25,27-32,34-35,39-40,51h,13-24,26h2,1-12h3,(h-,56,57,58,59,60,62);/q-1;+2/p-1/b33-25+;/t31-,32-,34-,35+,39-,40+,51-;/m1./s1 ykey: dsjxiqqmorjers-aggzhomasa-m smiles cc1(c)c2=n/c/1=c\c3c(c)c4c(=o)(c(=o)oc)\c\5=c/6\n=c(\c=c\7/n(n3c45)\c(=c/2)\c(=c7c)c(=o)c)(c)6ccc(=o)oc\c=c(/c)\ccc(c)ccc(c)cccc(c)c properties chemical formula mgc55h74n4o6 molar mass 911.524 g·mol−1 appearance light green to blue-green powder except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). infobox references structure chemical structures comparing porphin, chlorin, bacteriochlorin, and isobacteriochlorin. note relocation of c=c double bond between the two bacteriochlorin isomers. there are two π electrons (symbolized by π e−) for every double bond in the macrocycle. bacteriochlorophylls a, b, and g are bacteriochlorins, meaning their molecules have a bacteriochlorin macrocycle ring with two reduced pyrrole rings (b and d). bacteriochlorophylls c, d, e, and f are chlorins, meaning their molecules have a chlorin macrocycle ring with one reduced pyrrole ring (d). bacteriochlorophylls c to f occur in the form of closely related homologs with different alkyl groups attached to pyrrole rings b and c and are illustrated above in their simplest versions, esterified with the sesquiterpene alcohol farnesol. most of the variation occurs in the 8 and 12 positions and can be attributed to methyltransferase variation. bchl cs is a term for 8-ethyl,12-methyl homolog of bchl c. bacteriochlorophyll g has a vinyl group in ring (a), at position 8. biosynthesis the common biosynthetic precursor for bacteriochlorophylls is chlorophyllide a there are a large number of known bacteriochlorophylls but all have features in common since the biosynthetic pathway involves chlorophyllide a (chlide a) as an intermediate. chlorin-cored bchls (c to f) are produced by a series of enzymatic modifications on the sidechain of chlide a, much like how chl b, d, e are made. the bacteriochlorin-cored bchls a, b, g require a unique step to reduce the double bound between c7 and c8, which is performed by chlorophyllide a reductase (cor). isobacteriochlorins, in contrast, are biosynthesised from uroporphyrinogen iii in a separate pathway that leads, for example, to siroheme, cofactor f430 and cobalamin. the common intermediate is sirohydrochlorin.