CMorophyllides c

Abstract

"Chlorophyllides" c were obtained from methanol–tetrahydrofuran extracts of Phaeodactylum tricornutum by retention on an anion exchange resin. They were esterified (diazomethane) and separated by adsorption chromatography on powdered sucrose. The less adsorbed fraction was designated c1; the other c2. Both pigments possess two main visible absorption bands at ca. 629 and 582 nm. The ratios of the intensities of absorption in dioxane of band I to band II were 1.09 and 0.69, respectively.Treatment with methanolic hydrogen chloride yielded the respective chloroporphyrin e6 trimethyl esters, whose molecular weights (determined by mass spectrometry) were 634 and 632. The n.m.r. spectra showed the presence of the C7 acrylate group. Since both c1 and c2 yielded pyrroporphyrin XV, the structure of c2 requires C2 and C4 vinyl groups and that of c1 a vinyl group at either C2 or C4.Extinction coefficients of the phyllins and of the magnesium-free derivatives in various solvents were determined. Equations for the measurement of chlorophyllide c concentration in the presence of chlorophylls a and b are given.