Bacteriochlorophylls a, b, and g are bacteriochlorins, meaning their molecules have a bacteriochlorin macrocycle ring with two reducedpyrrole 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).[4]
Bacteriochlorophylls ctof 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.[5] Most of the variation occurs in the 8 and 12 positions and can be attributed to methyltransferase variation.[6] BChl cS is a term for 8-ethyl,12-methyl homolog of BChl c.[7]
Bacteriochlorophyll g has a vinyl group in ring (A), at position 8.[8]
The common biosynthetic precursor for bacteriochlorophylls is chlorophyllide a
There are a large number of known bacteriochlorophylls[4][9] but all have features in common since the biosynthetic pathway involves chlorophyllide a (Chlide a) as an intermediate.[10]
Chlorin-cored BChls (ctof) 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).[9]
^Niel, C. B. (1932). "On the morphology and physiology of the purple and green sulphur bacteria". Archiv für Mikrobiologie. 3: 1–112. doi:10.1007/BF00454965. S2CID19597530.
^ abSenge, Mathias O.; Smith, Kevin M. (2004). "Biosynthesis and Structures of the Bacteriochlorophylls". Anoxygenic Photosynthetic Bacteria. Advances in Photosynthesis and Respiration. Vol. 2. pp. 137–151. doi:10.1007/0-306-47954-0_8. ISBN0-7923-3681-X.
^Harada, Jiro; Shibata, Yutaka; Teramura, Misato; Mizoguchi, Tadashi; Kinoshita, Yusuke; Yamamoto, Ken; Tamiaki, Hitoshi (2018). "In Vivo Energy Transfer from Bacteriochlorophyll c , d , e , or f to Bacteriochlorophyll a in Wild-Type and Mutant Cells of the Green Sulfur Bacterium Chlorobaculum limnaeum". ChemPhotoChem. 2 (3): 190–195. doi:10.1002/cptc.201700164.
^Gloe, A; Risch, N (1 August 1978). "Bacteriochlorophyll cs, a new bacteriochlorophyll from Chloroflexus aurantiacus". Archives of Microbiology. 118 (2): 153–6. doi:10.1007/BF00415723. PMID697505. S2CID20011765.
^ abChew, Aline Gomez Maqueo; Bryant, Donald A. (2007). "Chlorophyll Biosynthesis in Bacteria: The Origins of Structural and Functional Diversity". Annual Review of Microbiology. 61: 113–129. doi:10.1146/annurev.micro.61.080706.093242. PMID17506685.
^Willows, Robert D. (2003). "Biosynthesis of chlorophylls from protoporphyrin IX". Natural Product Reports. 20 (6): 327–341. doi:10.1039/B110549N. PMID12828371.
^Battersby, Alan R. (2000). "Tetrapyrroles: The pigments of life: A Millennium review". Natural Product Reports. 17 (6): 507–526. doi:10.1039/B002635M. PMID11152419.