Synthesis, Reactivity and Structure of Chlorophylls

Senge, Ma­thias O.; Wiehe, Arno; Ryppa, Claudia

doi:10.1007/1-4020-4516-6_2

Cited by 28 publications

(29 citation statements)

References 56 publications

(43 reference statements)

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“…The main photosynthetic cofactors are the chlorophylls found in oxygenic PS plants (Chl a 7 and Chl b 38), and the bacteriochlorophylls present in purple bacteria such as Rhodobacter sphaeroides (BChl a; 8) and Blastochloris viridis (BChl b; 39). 149,150 At the heart of the initial stages of photosynthesis are the light-harvesting complexes (LHCs) 151 Over the years many crystal structures of chlorophyll derivatives have been reported. 88 In the context of the present discussion the most significant result of these was the observation of a wide range of conformations for chemically closely related pheophorbides and rhodochlorins.…”

Section: Chlorophyllsmentioning

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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Section: Chlorophyllsmentioning

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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“…Chlorophyll chemistry is governed by the aromatic character of the underlying tetrapyrrole moiety and functional group transformations in the side chains ( Figure 11) [67]. As a cyclic tetrapyrrole with a fused five-membered cyclopentanone ring, the ring system exhibits the typical features of a heteroaromatic compound.…”

Section: Fundamental Aspects Of Chlorophyll Chemistrymentioning

confidence: 99%

Chlorophylls, Symmetry, Chirality, and Photosynthesis

et al. 2014

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Chlorophylls are a fundamental class of tetrapyrroles and function as the central reaction center, accessory and photoprotective pigments in photosynthesis. Their unique individual photochemical properties are a consequence of the tetrapyrrole macrocycle, the structural chemistry and coordination behavior of the phytochlorin system, and specific substituent pattern. They achieve their full potential in solar energy conversion by working in concert in highly complex, supramolecular structures such as the reaction centers and light-harvesting complexes of photobiology. The biochemical function of these structures depends on the controlled interplay of structural and functional principles of the apoprotein and pigment cofactors. Chlorophylls and bacteriochlorophylls are optically active molecules with several chiral centers, which are necessary for their natural biological function and the assembly of their supramolecular complexes. However, in many cases the exact role of chromophore stereochemistry in the biological context is unknown. This review gives an overview of chlorophyll research in terms of basic function, biosynthesis and their functional and structural role in photosynthesis. It highlights aspects of chirality and symmetry of chlorophylls to elicit further interest in their role in nature.

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“…The book by Scheer 11 and a review by Hynninen 22 therein remain the most comprehensive treatises on Chl chemistry and function, while a comprehensive review on side chain transformation has recently been given by Pavlov and Ponomarev. 23 In recent years 7 …”

Section: Basic Structure and Reactivity Of Chlorophyllsmentioning

confidence: 99%

“…42 The ruffled distortion involves a twisting about the metal-nitrogen bond and is characterized by alternating displacement of the C m positions above and below the mean plane. A well know example is the S 4 -ruffled modification of (2,3,7,8,12,13,17,18-octaethylporphyrinato)nickel(II). 43 The saddle distortion involves the alternate displacement of the pyrrole rings above and below the mean plane while the C m positions remain more or less in plane.…”

Section: Conformational Analysis Of Porphyrinsmentioning

confidence: 99%

“…5,6 Parallel to studies on Chl a/b from Higher Plants, the last decades have seen many efforts to elucidate the structure, function and biosynthesis of photosynthetic pigments from unicellular organisms and photosynthetic bacteria. 7 In applied research chlorophylls are mainly used in solar energy conversion projects or as photosensitizers in photodynamic cancer therapy. 8,9 Industrially, phytochlorin and rhodochlorin derivatives have found some use as food additives and anti-odor compounds, often in form of simple plant extracts.…”

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