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Abstract

Chlorophylls, magnesium-containing tetrapyrrolic pigments of photosynthesis, are widely-distributed in Nature and participate in both light harvesting and in the transduction of light energy to chemical energy for the photosynthetic fixation of carbon dioxide. We briefly discuss the extensive role of various isotopic labelling techniques in elucidating the pathway of tetrapyrrole-pigment biosynthesis and we acknowledge the classic and meticulous research of David Shemin who, approximately 50 years ago, introduced isotopic tracer techniques with (15)N and (14)C isotopes to study the biosynthesis of the carbon/nitrogen macrocycle of haem, an iron tetrapyrrole. The main focus of this review is the application of mass spectrometry and (18)O labelling to the study of the incorporation of oxygen atoms from molecular oxygen or water into the periphery of the chlorophyll macrocycle during biosynthesis and their loss during degradation and light acclimation. In particular, we review the mechanism of formation of the isocyclic ring of chlorophylls, in higher plants, green algae and various photosynthetic bacteria, which concomitantly incurs formation of the 13(1)-oxo group that is present in all photosynthetically-active chlorophylls. In addition we discuss the formation of the ubiquitous 13(3)- and 17(3)-carboxyl groups and also the formation of the 7-formyl group of chlorophyll b and the 3-acetyl group of bacteriochlorophyll a.

Characterisation of uniformly 13C, 15N labelled bacteriochlorophyll a and bacteriopheophytin a in solution and in solid state: complete assignment of the 13C, 1H and 15N chemical shifts

“…[18] Isotopic replacement of pigments and a lipid in chlorosomes and characterisation of the chlorosomes are described in Ref. [19].…”

Nitric Oxide Is Associated With Heterosis of Salinity Tolerance in Brassica napus L.

“…The TCA cycle is one of the key ways of cellular processes of carbon and nitrogen metabolism in plant mitochondria and is also important for fueling respiratory electron transport and, thus, ATP synthesis (Taylor et al, 2004;Kosová et al, 2011). Most importantly, the TCA cycle could provide the energy and carbon skeleton for the protein synthesis related to chlorophyll (Nabeta et al, 1998;Porra and Scheer, 2000) and proline biosynthesis (Hildebrandt et al, 2015). Previous biochemical and proteomic analysis revealed that TCA cycle enzymes were FIGURE 8 | Schematic diagram of the potential role of NO in the heterosis of B. napus against salt stress at the proteomic and physiological levels.…”

De Novo Synthesis of Bacteriochlorins Bearing Four Trideuteriomethyl Groups

“…Biosynthetic incorporation of isotopic atoms can be achieved by use of isotopically enriched precursors, such as 15 N-ammonium, 13 C-carbonate, H 2 18 O, and/or 2 H 2 O, which afford global isotopic enrichment [3][4][5][6][7][8][9][10][11]. Alternatively, use of more advanced precursors with site-specific isotopic substitution affords greater selectivity [5,[12][13][14][15][16][17]. Incorporation of 26 Mg as the metal chelate also has been achieved via biosynthesis with use of 26 MgSO 4 [18].…”