Chlorophyllc refers to forms ofchlorophyll found in certain marine algae, including the photosyntheticChromista (e.g.diatoms andbrown algae) anddinoflagellates.[1][2][3] These pigments are characterized by their unusual chemical structure, with aporphyrin as opposed to thechlorin (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.[2]
It has a blue-green color and is anaccessory pigment, particularly significant in its absorption of light in the 447–520 nm wavelength region.[3] Likechlorophylla andchlorophyllb, it helps the organism gather light and passes a quanta of excitation energy through the light harvesting antennae to thephotosynthetic reaction centre.[2]
Chlorophyllc can be further divided into chlorophyllc1, chlorophyllc2,[3] and chlorophyllc3,[4] plus at least eight other more recently found subtypes.[5]
Chlorophyllc1 is a common form of chlorophyllc. It differs from chlorophyllc2 in its C8 group, having an ethyl group instead of vinyl group (C-C single bond instead of C=C double bond).Itsabsorption maxima are around 444, 577, 626 nm and 447, 579, 629 nm indiethyl ether andacetone respectively.[6]
Chlorophyllc2 is the most common form of chlorophyllc.[7] Its absorption maxima are around 447, 580, 627 nm and 450, 581, 629 nm in diethyl ether and acetone respectively.[6]
Chlorophyllc3 is a form of chlorophyllc found in microalgaEmiliania huxleyi, identified in 1989.[4]Its absorption maxima are around 452, 585, 625 nm and 452, 585, 627 nm in diethyl ether and acetone respectively.[6]
Chlorophyllc synthesis branches off early from the typicalChlorophyllide synthesis pathway, afterdivinylprotochlorophyllide (DV-PChlide) is formed. It has been established that DV-PChlide and MV-PChlide are processed directly by a 171 oxidase (CHLC, chlorophyllc synthase) into Chlc2 and Chlc1, respectively.[8] 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."[8][9]An 8-vinyl reductase (elaborating on the promiscuous behavior of ferredoxin-type3,8-divinyl chlorophyllide reductase) could also convert Chlc2 into Chlc1. The two steps could be swapped for the same effect.[10]
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