Chlorophylls, Symmetry, Chirality, and Photosynthesis

Senge, Ma­thias O.; Ryan, Aoife A.; Letchford, Kristie A.; MacGowan, Stuart A.; Mielke, Tamara

doi:10.3390/sym6030781

Cited by 178 publications

(132 citation statements)

References 282 publications

(300 reference statements)

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“…236,237 It functions as the excitation energy transfer (EET) intermediate between the chlorosome baseplate and the RCs of the photosynthetic green sulphur bacteria and contains seven BChl a pigments. 125,213,237,238 Fig. 21 Illustration of the FMO protein monomeric asymmetric unit.…”

mentioning

confidence: 99%

Conformational control of cofactors in nature – the influence of protein-induced macrocycle distortion on the biological function of tetrapyrroles

2015

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Tetrapyrrole-containing proteins are one of the most fundamental classes of enzymes in nature and it remains an open question to give a chemical rationale for the multitude of biological reactions that can be catalyzed by these pigmentprotein complexes. There are many fundamental processes where the same (i.e., chemically identical) porphyrin cofactor is involved in chemically quite distinct reactions. For example, heme is the active cofactor for oxygen transport and storage (hemoglobin, myoglobin) and for the incorporation of molecular oxygen in organic substrates (cytochrome P 450 ). It is involved in the terminal oxidation (cytochrome c oxidase) and the metabolism of H 2 O 2 (catalases and peroxidases) and catalyzes various electron transfer reactions in cytochromes. Likewise, in photosynthesis the same chlorophyll cofactor may function as a reaction center pigment (charge separation) or as an accessory pigment (exciton transfer) in light harvesting complexes (e.g., chlorophyll a). Whilst differences in the apoprotein sequences alone cannot explain the often drastic differences in physicochemical properties encountered for the same cofactor in diverse protein complexes, a critical factor for all biological functions must be the close structural interplay between bound cofactors and the respective apoprotein in addition to factors such as hydrogen bonding or electronic effects. Here, we explore how nature can use the same chemical molecule as a cofactor for chemically distinct reactions using the concept of conformational flexibility of tetrapyrroles. The multifaceted roles of tetrapyrroles are discussed in the context of the current knowledge on distorted porphyrins. Contemporary analytical methods now allow a more quantitative look at cofactors in protein complexes and the development of the field is illustrated by case studies on hemeproteins and photosynthetic complexes. Specific tetrapyrrole conformations are now used to prepare bioengineered designer proteins with specific catalytic or photochemical properties.

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confidence: 99%

Conformational control of cofactors in nature – the influence of protein-induced macrocycle distortion on the biological function of tetrapyrroles

2015

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“…Pyridine, Ar-atm., refluks 6 h (23%) H Scheme 2. The synthesis route from Chl a (1) to its enol derivative (4) Examination of the Dd C -values in Table 2 for the enol derivatives 3 and 4 is interesting, because no corresponding comparison has been previously performed. Most prominent Dd C -values concern carbons 13, 13 1 Tables 1 and 2, it can be concluded that the enol derivatives 3 and 4 are still diamagnetic and aromatic, although their ring current is weaker than that of Chl a due to the expansion of the p-system to include the isocyclic ring E. c The P5-P16 part of the phytyl group spectrum was as reported in Ref.…”

Section: Resultsmentioning

confidence: 99%

“…1, 1) and Chl b (Fig. 1, replace the C7-CH 3 group with a formyl) are Mg(II)-complexes of aromatic tetrapyrrolic heterocycles, which occur as indispensable photosynthetic pigments in all higher plants, being primarily responsible for the conversion of solar energy into chemical energy [1][2][3][4]. The isocyclic ring, also called exocyclic ring or cyclopentanone ring, E of all chlorophylls (except the chlorosome chlorophylls [3]) is a substituted b-keto ester and therefore has a strong tendency to enolize [5,6].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of chlorophyllaenol derivatives: Chlorophyllatert-butyldimethylsilyl-enol ether and 131-deoxo-131, 132-didehydro-chlorophylla

Hynninen

Mesilaakso²

2016

J. Porphyrins Phthalocyanines

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Using the sterically hindered base, 1,8-diazabicyclo[5.4.0]undec-7-ene, for enolization and tert-butyldimethylsilyl-trifluoromethanesulfonate for silylation, chlorophyll (Chl) a produced after 15 min at 0 °C in deaerated pyridine solution under argon, after work-up and chromatographic purification on a sucrose column, tert-butyldimethylsilyl-enol ether of Chl a in a yield of 77%. The 13 1 -deoxo-13 1 ,13 2 -didehydro-chlorophyll a, was obtained in a yield of 23% through a reaction sequence, where Chl a was first reduced with sodium borohydride to 13 1 (R,S)-hydroxy-Chl a, which via demetalation yielded 13 1 (R,S)-hydroxypheophytin a. In the presence of the sterically hindered base, 1,8-bis(dimethylamino) naphthalene, trifluoroacetylimidazole dehydrated 13 1 (R,S)-hydroxypheophytin a to 13 1 -deoxo-13 1 ,13 2 -didehydro-pheophytin a, which after metalation yielded 13 1 -deoxo-13 1 ,13 2 -didehydro-Chl a. Using 1,8-bis(dimethylamino)naphthalene and trifluoroacetylimidazole, the straight conversion of 13 1 (R,S)-hydroxy-Chl a to 13 1 -deoxo-13 1 ,13 2 -didehydro-Chl a was found unsuccessful. The major products were characterized by electronic absorption spectra (UV-vis) and practically completely assigned 1 H and 13 C NMR spectra. Some intermediates of the syntheses were also characterized by ESI-TOF mass spectra. Compared with Chl a, the macrocyclic ring-current in the synthesized Chl a enol derivatives was found weakened by the expansion of the p-system to include the isocyclic ring E. Nevertheless, these enol derivatives were still considered to be diamagnetic and aromatic. The possibility of the functional role of the enol derivatives of chlorophyll in photosynthesis is discussed.

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“…This indicates a possible β-galactoside-recognized protein specificity for 555b, 556b and 557 [279] . Due to their excellent uptake and photophysical properties phyto-and rhodochlorin derivatives have remained at the forefront of efforts to develop better PS [283] . Thus they present ideal candidates to investigate the influence of sugar units.…”

Section: Hydroporphyrinsmentioning

confidence: 99%

Chemical Synthesis and Medicinal Applications of Glycoporphyrins

Moylan¹,

Scanlan²,

Senge

2015

CMC

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Abstract:This review presents an in-depth overview of the modification of porphyrins with bioconjugates and their applications in medicine today. Porphyrin bioconjugates ranging from nucleotides to steroids are under active scrutiny. However, carbohydrates have been at the forefront of such research in recent years and offer significant potential. This is attributed to their own selectivity to lectins on the surface of cancer cells and their influence on the amphiphilicity of the porphyrin macrocycle. These characteristics and the tendency of porphyrin photosensitizers to accumulate in tumor tissues make glycoporphyrins promising candidates for use as photosensitizers. Thus, a detailed overview of the synthesis and biological evaluation of glycoporphyrins is given with a particular focus on their applications in photodynamic therapy and their future prospects as drug candidates have been reported.

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Chlorophylls, Symmetry, Chirality, and Photosynthesis

Cited by 178 publications

References 282 publications

Conformational control of cofactors in nature – the influence of protein-induced macrocycle distortion on the biological function of tetrapyrroles

Conformational control of cofactors in nature – the influence of protein-induced macrocycle distortion on the biological function of tetrapyrroles

Synthesis and characterization of chlorophyllaenol derivatives: Chlorophyllatert-butyldimethylsilyl-enol ether and 131-deoxo-131, 132-didehydro-chlorophylla

Chemical Synthesis and Medicinal Applications of Glycoporphyrins

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