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Chlorophyll b

Chlorophyll b is a green photosynthetic pigment primarily found in higher plants and green algae, where it functions as an accessory light-harvesting molecule that broadens the spectrum of usable sunlight by absorbing wavelengths not efficiently captured by chlorophyll a and transferring the excitation energy to the photosynthetic reaction centers.^[1] Its molecular formula is C55H70MgN4O6, with a molar mass of 907.5 g/mol.^[2] It appears as a green solid that is soluble in organic solvents like ethanol and acetone but insoluble in water.^[3] Structurally, chlorophyll b is a chlorin derivative, consisting of a porphyrin ring coordinated to a central magnesium ion, similar to chlorophyll a but distinguished by a formyl (-CHO) group at the C7 position of the macrocycle instead of a methyl (-CH3) group.^[4] This substitution shifts its absorption maxima to approximately 450–460 nm in the blue-violet region and 640–650 nm in the orange-red region, enabling it to capture photons in these wavelengths with higher efficiency than chlorophyll a, whose peaks are at 430 nm and 662 nm.^[5] These optical properties make chlorophyll b essential for optimizing light harvesting under varying environmental conditions, such as shaded or dense canopies where blue and far-red light predominate.^[6] In photosynthesis, chlorophyll b is predominantly located in the peripheral light-harvesting complexes (LHCs) of photosystems I and II in the thylakoid membranes of chloroplasts, where it binds to proteins like Lhcb1 and facilitates energy transfer via Förster resonance energy transfer (FRET) to chlorophyll a molecules in the core antenna or reaction centers.^[7] Unlike chlorophyll a, which directly participates in charge separation, chlorophyll b does not form the primary electron donor but plays a supportive role in stabilizing LHC assembly and protecting against photooxidative damage by dissipating excess energy.^[8] Mutants deficient in chlorophyll b exhibit reduced photosynthetic efficiency and altered antenna sizes, underscoring its importance for plant adaptation to light stress and growth in low-light environments.^[9]

Chemical Structure and Properties

Molecular Formula and Structure

Chlorophyll b has the molecular formula C_{55}H_{70}MgN_4O_6 and a molecular weight of 907.49 g/mol.^[2] The core structure of chlorophyll b consists of a chlorin macrocycle, a tetrapyrrole derivative with a porphyrin-like ring system where ring D is partially reduced (single bond between C17 and C18), and a central magnesium ion (\mathrm{Mg}^{2+}) coordinated to the four pyrrole nitrogen atoms. A characteristic feature is the fused five-membered cyclopentanone ring (ring V) attached at positions C13 and C15, bearing a carbomethoxy group (-\mathrm{COOCH_3}) at the chiral C13^2 position. Key substituents on the macrocycle include a vinyl group (-\mathrm{CH=CH_2}) at C3 and an ethyl group (-\mathrm{CH_2CH_3}) at C8, while the distinguishing feature from chlorophyll a is the formyl group (-\mathrm{CHO}) at C7 instead of a methyl group (-\mathrm{CH_3}). At C17, a propionic acid side chain (-\mathrm{CH_2CH_2COOH}) is esterified with phytol, a branched C_{20} trans-alkene alcohol chain specifically (2E,7R,11R)-3,7,11,15-tetramethylhexadec-2-en-1-ol, conferring hydrophobicity to the molecule.^[10]^[2] Chlorophyll b exhibits specific stereochemistry at its three chiral centers in the macrocycle: (13^2R) configuration at the carbomethoxy-bearing carbon, and (17S,18S) at the reduced ring D, resulting in a trans orientation between the C13^2-carboxylic acid derivative and the C17 propionic acid side chain. This stereochemical arrangement contributes to the molecule's overall conformation and stability within photosynthetic complexes. The replacement of the C7 methyl with a formyl group in chlorophyll b enhances its polarity due to the carbonyl, increasing solubility in polar solvents compared to chlorophyll a, and subtly alters reactivity, particularly in oxidation and coordination behaviors, while maintaining similar macrocyclic planarity.^[10]^[11] The structure can be represented textually with standard numbering as follows:

Macrocycle: Chlorin with Mg at center; rings A–D, reduced at C17–C18.
Ring A: Methyl at C2, vinyl at C3.
Ring B: Formyl at C7, ethyl at C8.
Ring C: Methyl at C12; C13^1: carbonyl in ring V; C13^2: -CH(CH_3)COOCH_3, with (R) config; C15: part of ring V.
Ring D: Propionic acid phytol ester at C17, methyl at C18; (S) config at C17 and C18.
Meso positions (C5, C10, C15, C20): H (C15 shared with ring V).

For clarity, the key distinguishing elements are highlighted in the description above, as full atomic-level depiction is typically visualized in diagrams.^[10]^[12]

Spectroscopic Properties

Chlorophyll b exhibits characteristic absorption peaks in the blue and red regions of the visible spectrum, reflecting its role in capturing light for photosynthesis. In vivo, in the protein environment of light-harvesting complexes, these peaks are shifted to approximately 475 nm in the blue region and 652 nm in the red region, with a notable shoulder in the red region around 620–630 nm that distinguishes it from chlorophyll a.^[13] In vitro, these peaks occur at approximately 453 nm (blue) and 642 nm (red) in diethyl ether. The molar extinction coefficients are high, on the order of $10^5 M^{-1} cm^{-1}, with specific values of approximately $1.59 \times 10^5 M^{-1} cm^{-1} at the blue peak (453 nm) and $4.0 \times 10^4 M^{-1} cm^{-1} at the red peak (642 nm) in diethyl ether.^[14]^[15] These properties follow the Beer-Lambert law, where absorbance A = \epsilon c l, with \epsilon as the molar extinction coefficient, c the concentration, and l the path length; for chlorophyll b, the high \epsilon values enable sensitive quantification in extracts.^[14] The fluorescence properties of chlorophyll b include emission primarily at 650–660 nm when excited in the absorption bands, such as at 435 nm. Its quantum yield is lower than that of chlorophyll a, approximately 0.12 in diethyl ether compared to 0.25–0.32 for chlorophyll a, attributable to differences in molecular structure influencing non-radiative decay pathways.^[14]^[16] Chlorophyll b is highly lipophilic owing to its phytyl tail, rendering it insoluble in water but readily soluble in organic solvents such as acetone and ethanol, which are commonly used for extraction. It degrades under exposure to light and oxygen through pheophytinization, involving the loss of the central magnesium ion to form pheophytin b, which shifts the absorption spectrum and alters color from green to olive-brown.^[17] Environmental factors like solvent polarity and pH influence the spectroscopic bands of chlorophyll b. In more polar solvents like methanol, the absorption peaks exhibit a red shift compared to non-polar solvents such as diethyl ether, due to solvation effects on the formyl group; for instance, the red peak shifts from ~645 nm in ether to ~652 nm in methanol.^[18] Acidic pH accelerates pheophytinization, broadening and shifting bands, while alkaline conditions may induce minor blue shifts in the Q-band.^[19]^[20]

Occurrence and Distribution

In Vascular Plants

Chlorophyll b is abundant in the leaves of vascular plants, particularly angiosperms and gymnosperms, where it typically comprises 20-25% of the total chlorophyll content alongside the dominant chlorophyll a.^[21] This proportion supports efficient light harvesting in terrestrial environments, with chlorophyll b contributing to the expansion of the absorption spectrum beyond that of chlorophyll a alone. In angiosperms, such as beech (Fagus sylvatica) and oak (Quercus robur), chlorophyll b plays a key role in antenna functions, as evidenced by its integration into photosynthetic complexes.^[22] Similarly, gymnosperms like ginkgo (Ginkgo biloba) exhibit comparable chlorophyll profiles, underscoring its widespread distribution across seed-producing vascular plants.^[22] Within vascular plants, chlorophyll b is predominantly localized in the light-harvesting complexes (LHCs) associated with photosystem II, embedded in the thylakoid membranes of chloroplasts. These complexes, particularly LHCII, bind chlorophyll b to facilitate energy capture and transfer, with spectroscopic studies confirming its distinct excitation properties in these structures.^[23] This localization enhances the photosynthetic efficiency by positioning chlorophyll b in peripheral antenna arrays that funnel absorbed energy to the reaction centers. The typical chlorophyll b:a ratio in C3 vascular plants ranges from 0.2 to 0.5, determined through spectrophotometric analysis of leaf extracts, reflecting a balanced integration for optimal light utilization.^[22]^[24] The abundance of chlorophyll b varies by plant type and environmental conditions, with higher ratios observed in shade-adapted vascular plants to broaden light capture in low-irradiance settings. In shade-tolerant species, chlorophyll b can reach up to 30% of total chlorophyll, lowering the a:b ratio to as low as 2.5:1 or below, which aids acclimation to understory habitats.^[25] Conversely, sun-exposed species maintain lower chlorophyll b proportions, with ratios closer to 3:1, prioritizing efficiency under high light.^[26] This plasticity in chlorophyll b distribution exemplifies physiological adaptations in vascular plants for diverse terrestrial niches.^[27]

In Algae and Cyanobacteria

Chlorophyll b is present in green algae of the division Chlorophyta, where it functions similarly to its role in vascular plants as an accessory pigment in light-harvesting complexes. In these organisms, chlorophyll b typically comprises 20-30% of the total chlorophyll content, with a common chlorophyll a to b ratio of approximately 3:1, enabling efficient energy capture in both freshwater and marine habitats.^[21] This pigment is essential for the photosynthetic apparatus of diverse Chlorophyta species, such as Chlamydomonas, which dominate various aquatic ecosystems.^[1] In certain cyanobacteria, known as prochlorophytes, chlorophyll b occurs alongside chlorophyll a in a prokaryotic context, marking a unique adaptation among oxygenic photosynthesizers. Genera like Prochlorococcus and Prochloron lack phycobilins, the typical light-harvesting pigments of other cyanobacteria, and instead rely on chlorophyll b for photon absorption.^[28] Prochlorococcus, a dominant picocyanobacterium in oligotrophic oceans, exhibits chlorophyll a/b ratios ranging from 0.6 to 13 across strains, allowing up to near-equimolar levels of chlorophyll b in some deep-water adapted forms.^[29] The symbiotic Prochloron, first identified in 1975 as the initial prokaryote containing chlorophyll b, resides within marine ascidians and shares structural similarities with plant chlorophyll b.^[30] Chlorophyll b levels vary across algal groups, with notably lower or absent concentrations in lineages derived from red algae, such as cryptophytes, while it is entirely lacking in most red (Rhodophyta) and brown (Phaeophyceae) algae, which utilize chlorophyll c as accessory pigments instead.^[31] Ecologically, chlorophyll b facilitates adaptation to the spectral quality of underwater light, particularly the blue-green wavelengths (450-500 nm) that penetrate deeper water columns, enhancing light harvesting for prochlorophytes in open-ocean environments and green algae in coastal or freshwater settings.^[29] This distribution underscores chlorophyll b's role in enabling primary productivity in stratified aquatic systems where red and far-red light are attenuated.^[21]

Role in Photosynthesis

Light Absorption and Energy Transfer

Chlorophyll b serves as an accessory pigment in the light-harvesting complexes (LHCs) of plants, primarily absorbing light in the blue region of the spectrum, with significant absorption extending from approximately 400 to 500 nm, which complements the absorption profile of chlorophyll a and broadens the overall light-capturing capacity of the photosynthetic apparatus.^[32] This extended blue absorption is particularly advantageous for capturing wavelengths enriched in shaded or canopy-filtered environments, such as forest understories, where direct sunlight is limited.^[6] Upon photon absorption, chlorophyll b enters an excited singlet state (S1), and the excitation energy is efficiently transferred to chlorophyll a molecules within the LHCs through Förster resonance energy transfer (FRET), a non-radiative process governed by dipole-dipole coupling between the pigments.^[32] This transfer occurs on picosecond timescales with efficiencies typically exceeding 90%, often approaching 100%, due to favorable spectral overlap between the emission of chlorophyll b and the absorption of chlorophyll a.^[33] Seminal studies, such as those by Duysens, first demonstrated this directional energy migration from accessory chlorophylls like b to the reaction center-associated chlorophyll a.^[34] Experimental evidence from fluorescence quenching studies supports the role of chlorophyll b as a peripheral antenna pigment, where its fluorescence is rapidly quenched upon transfer of excitation energy to chlorophyll a, confirming the high efficiency of this process in vivo.^[32] Two-dimensional electronic spectroscopy has further revealed coherent dynamics in these transfers, underscoring the quantum mechanical nature of the energy funneling in LHCs.^[32] The adaptive significance of chlorophyll b lies in its ability to enhance photosynthetic efficiency under variable light conditions, particularly in low-light or shade-adapted scenarios, by optimizing energy capture from the depleted blue spectrum and ensuring rapid delivery to the photosynthetic reaction centers.^[6] This mechanism allows plants to maintain productivity in heterogeneous light environments without requiring structural changes to the core photosystems.^[35]

Integration in Photosystems

Chlorophyll b is primarily associated with photosystem II (PSII) through its integration into the light-harvesting complex II (LHCII), the major antenna system that forms trimers to capture light energy.^[36] Within each LHCII monomer, chlorophyll b occupies specific binding sites that enable its coordination with chlorophyll a and carotenoids, such as lutein and neoxanthin, forming a pigment network essential for efficient excitation energy collection.^[36] The stoichiometry typically includes approximately 6 chlorophyll b molecules per LHCII monomer, alongside 8 chlorophyll a and 4 carotenoids, allowing for optimized light absorption in the blue-green spectrum and subsequent transfer to the PSII reaction center.^[36] Cryo-electron microscopy (cryo-EM) structures of the PSII-LHCII supercomplex reveal the precise positions of chlorophyll b within LHCII trimers, positioned at the periphery to facilitate directional energy funneling toward the PSII core, including the reaction center chlorophyll pair P680.^[37] These models demonstrate how chlorophyll b's excitonic coupling with chlorophyll a creates a gradient that directs excitation energy inward, enhancing the overall quantum efficiency of PSII photochemistry.^[37] This arrangement supports rapid energy transfer from chlorophyll b to chlorophyll a within the antenna, minimizing losses and balancing excitation between photosystems.^[38] The integration of LHCII, rich in chlorophyll b, is dynamically regulated by light-induced phosphorylation of its constituent proteins, which modulates the migration of LHCII trimers between PSII and photosystem I (PSI) to balance electron flow under varying light conditions.^[39] This state transition mechanism ensures adaptive energy distribution, with phosphorylated LHCII associating more readily with PSI during excess PSII excitation.^[39] Mutational studies in plants, such as the Arabidopsis chlorina-1 mutants defective in chlorophyll b synthesis due to disruptions in the chlorophyllide a oxygenase gene, exhibit pale green phenotypes and reduced PSII efficiency, underscoring chlorophyll b's critical role in antenna assembly and light harvesting.^[40] These mutants display diminished LHCII accumulation, leading to lower photochemical yields and impaired photosynthetic performance under normal growth conditions.^[40]

Biosynthesis and Metabolism

Synthetic Pathway

The biosynthesis of chlorophyll b branches from the chlorophyll a pathway at the chlorophyllide a stage, where the C7 methyl group is oxidized to a formyl group through a series of oxygenation reactions. This pathway shares initial steps with chlorophyll a synthesis, beginning from magnesium protoporphyrin IX, which is methylated to form Mg-protoporphyrin IX monomethyl ester by the enzyme Mg-protoporphyrin IX methyltransferase (CHLM). Subsequent cyclization and reduction steps lead to divinyl protochlorophyllide a, which is then reduced to chlorophyllide a by light-dependent protochlorophyllide oxidoreductase (LPOR). At this point, the pathway diverges for chlorophyll b production.^[41]^[42] The key enzymatic step in chlorophyll b formation is catalyzed by chlorophyllide a oxygenase (CAO), a Rieske-type non-heme iron-dependent monooxygenase that performs two sequential C-H bond activations using molecular oxygen (O₂) and α-ketoglutarate as cosubstrates. CAO first converts chlorophyllide a to 7-hydroxymethyl chlorophyllide a (an intermediate), followed by further oxidation to chlorophyllide b. This reaction requires electron transfer, often supported by ferredoxin or non-native reductases in vitro. Chlorophyllide b is then esterified with phytol by chlorophyll synthase (CHLG) to yield mature chlorophyll b.^[41]^[42]^[40] CAO activity and expression are tightly regulated to balance chlorophyll a and b levels. In Arabidopsis thaliana, the CAO gene is upregulated by light exposure, with mRNA levels increasing rapidly upon transfer from dim to moderate light (e.g., from 5 to 60 μmol·m⁻²·sec⁻¹), correlating with enhanced chlorophyll b accumulation under shade conditions. Feedback inhibition occurs via chlorophyll a levels; accumulation of chlorophyll a suppresses CAO expression, while chlorophyll b-deficient states elevate it approximately twofold, preventing overproduction of light-harvesting complexes. Overexpression of CAO in transgenic plants increases chlorophyll b synthesis and lowers the chlorophyll a/b ratio, particularly in low-light environments.^[40]^[43] Genetic studies in the 1990s provided key evidence for the pathway, with the CAO gene cloned from Arabidopsis thaliana and shown to restore chlorophyll b synthesis in mutants. Chlorophyll b-less mutants such as cbs1–cbs6 harbor deletions in the CAO locus, while point mutations (e.g., V274E) or null alleles (e.g., 213-bp deletion in ch1-3) abolish enzyme function, resulting in no detectable chlorophyll b and impaired light-harvesting complex assembly. Complementation with wild-type CAO genomic fragments confirms its essential role.^[42]^[40]

Degradation Processes

Chlorophyll b degradation primarily occurs through a catabolic pathway initiated by specific enzymatic reductions, ensuring the pigment is converted to forms compatible with the broader chlorophyll breakdown process. The initial step involves the reduction of the formyl group at the C7 position, catalyzed by chlorophyll b reductases encoded by the NYC1 (non-yellow coloring 1) and NOL (NYC1-like) genes in Arabidopsis thaliana. These enzymes convert chlorophyll b to 7-hydroxymethyl chlorophyll a, which is further reduced to chlorophyll a by 7-hydroxymethyl chlorophyll a reductase (HCAR), thereby channeling chlorophyll b into the chlorophyll a degradation route before dephytylation or magnesium removal. This chlorophyll b-specific initiation prevents accumulation of potentially toxic intermediates and is essential for efficient turnover.^[44] Following conversion to chlorophyll a equivalents, the pathway proceeds with dephytylation mediated by chlorophyllase, yielding chlorophyllide a, although in senescence contexts, alternative routes involving pheophytinase (PPH) on Mg-depleted forms may predominate. Magnesium removal then occurs via stay-green (SGR) proteins, producing pheophorbide a from chlorophyllide a. The key ring-opening step is catalyzed by pheophorbide a oxygenase (PaO), which preferentially acts after conversion to pheophorbide a but can process pheophorbide b, leading to the formation of red chlorophyll catabolite (RCC) and subsequent linear tetrapyrroles such as primary fluorescent chlorophyll catabolites (pFCCs). These are further modified to non-toxic, colorless non-fluorescent chlorophyll catabolites (NCCs) by reductases and isomerases, facilitating safe export to the vacuole. The structural vulnerability of the formyl group in chlorophyll b necessitates its prior reduction to avoid stalled degradation.^[44]^[45]^[46] Degradation of chlorophyll b is triggered under conditions such as leaf senescence, herbivory, and environmental stresses including drought, resulting in up to 90% loss of total pigments to prevent photooxidative damage. During senescence in vascular plants, these processes dismantle light-harvesting complexes, with NYC1 and NOL expression upregulated to prioritize chlorophyll b breakdown ahead of chlorophyll a. Ecologically, this catabolism enables nutrient remobilization, particularly of magnesium and nitrogen, from senescing tissues to support reproductive growth or storage organs, enhancing plant fitness under resource-limited conditions.^[47]^[48]

History and Research

Discovery and Isolation

The recognition of chlorophyll b as a distinct pigment began in the mid-19th century with spectroscopic observations suggesting that the green coloring matter in plants consisted of more than one component. In 1864, George Gabriel Stokes demonstrated through fluorescence and absorption studies that chlorophyll was a mixture of at least two green pigments, based on differences in their spectral properties when extracted from leaves.^[49]^[50] This challenged the prevailing view of chlorophyll as a single entity, though isolation proved challenging due to the pigments' instability and similarity. Spectroscopic distinctions were further advanced by Henry Clifton Sorby in 1873, who identified two absorption bands corresponding to distinct chlorophyll components. In 1879, Felix Hoppe-Seyler employed gentle solvent extraction methods to isolate chlorophyll while avoiding harsh chemical treatments that had previously degraded samples; he prepared crystalline derivatives like phylloporphyrin and confirmed their relation to blood pigments through chemical analysis, though full separation of the two green components remained elusive.^[49]^[51] Early isolation techniques relied on alcohol extraction from macerated leaves, followed by fractionation with solvents like ether or petroleum ether to yield green bands, but purity remained low and the pigments were often confused or contaminated with degradation products. A major advance came in 1906 when Mikhail Tswett introduced adsorption chromatography, passing alcohol extracts of plant leaves through calcium carbonate columns to resolve pigments into colored bands; this separated the two chlorophylls as distinct green fractions, alongside yellow carotenoids, confirming their individuality without chemical alteration.^[52]^[53] Richard Willstätter built on this in the early 1900s, refining isolation via repeated solvent partitioning and crystallization, isolating pure chlorophyll a and b by 1907 and naming them based on their absorption maxima—chlorophyll a at longer wavelengths and b at shorter, bluish-green ones—thus dispelling misconceptions of their identity.^[49]^[54] His work, culminating in the 1915 Nobel Prize, established their magnesium-containing structures and variable ratios in plants. In the 1930s, quantitative assays emerged to measure chlorophyll b alongside a, using spectrophotometry on acetone or ethanol extracts to determine ratios via specific absorption coefficients; these revealed chlorophyll b comprising 20-30% of total chlorophyll in shade-adapted plants, varying with light conditions and species, and provided tools for ecological studies of photosynthetic efficiency.^[55]^[56]

Structural Determination

The structural determination of chlorophyll b began in the early 20th century with partial elucidations through degradation studies. Richard Willstätter, in his pioneering work from 1905 to 1915, isolated chlorophyll b as a distinct pigment and proposed its empirical formula as C55H70O6N4Mg, based on elemental analysis and degradation products like methylphytol and porphyrin derivatives, though the full macrocyclic arrangement remained unclear.^[54]^[57] Hans Fischer advanced this significantly in the 1930s and 1940s, building on his 1930 Nobel Prize-winning synthesis of hemin and porphyrins, which provided insights into tetrapyrrole frameworks. By 1940, Fischer's group proposed the complete gross structure of chlorophyll b, confirming it as a chlorin derivative with a formyl group (-CHO) at the C7 position of ring B, distinguishing it from chlorophyll a (which has a methyl group there), and including a phytol ester chain at C17. This was achieved through exhaustive degradation, reconstitution from pyrrole subunits, and comparison with synthetic analogs, resolving earlier ambiguities in ring saturation and side-chain configurations.^[58]^[59] Mid-20th-century spectroscopic techniques further validated Fischer's structure. UV-Vis spectroscopy revealed distinct absorption maxima for chlorophyll b at around 645 nm, attributable to the conjugated formyl group, while mass spectrometry in the 1950s confirmed the molecular weight and fragmentation patterns consistent with the C55H70O6N4Mg formula. Nuclear magnetic resonance (NMR) studies in the 1960s, including fully deuterated analogs, provided precise assignments for proton environments, verifying the C7 formyl substitution and phytol chain length (C20H39OH) while addressing post-1950s debates on ring V saturation and the exact positioning of the two additional hydrogens in the chlorin macrocycle.^[60]^[61] Structural refinements continued with crystallographic methods. In the 1990s, electron crystallography of the light-harvesting chlorophyll a/b-protein complex (LHCII) at 3.4 Å resolution revealed chlorophyll b's integration within the protein scaffold, confirming its orientation and coordination to histidine residues. Higher-resolution X-ray crystallography of LHCII in 2004 at 2.72 Å provided atomic details of the formyl group interactions. Post-2010 cryo-electron microscopy (cryo-EM) structures, such as those of plant photosystem II supercomplexes at resolutions below 3 Å, have further contextualized chlorophyll b's binding sites and conformational dynamics in native assemblies.^[62]^[63]^[64]

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This gene, AtCAO, is mutated in both leaky and null chlorina1 alleles, and DNA sequence changes cosegregate with the mutant phenotype. AtCAO mRNA levels are ...
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Research Progress in the Interconversion, Turnover and ...
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Thus, our data collectively indicate that chlorophyll b degradation is a key step in the degradation of LHCII and the thylakoid membrane during senescence.
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Evolution of chlorophyll degradation is associated with plant ...
Significance Statement. Chlorophyll, the central pigment of photosynthesis, is highly photo‐active and degraded enzymatically during leaf senescence.
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Nobel Prize in Chemistry 1915 - Presentation - NobelPrize.org
Willstätter won for elucidating chlorophyll's chemical nature, proving magnesium is integral, and laying the foundation for plant chemistry research.
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This month's "Milestones in Chromatography" column commemorates the centenary of the two publications of M.S. Tswett first using the term "chromatography."
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Willstätter discovered two primary forms of chlorophyll, alpha and beta, and that they are magnesium complexes. He used innovative techniques to isolate and ...
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The green molecule | Feature - Chemistry World
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Hans Fischer | Encyclopedia.com
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SPECTRAL ABSORPTION PROPERTIES OF ORDINARY ... - PubMed
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Chlorophyll B. Totalzuordnung des 13C-NMR-spektrums
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Crystal structure of spinach major light-harvesting complex at 2.72 A ...
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Light harvesting in oxygenic photosynthesis: Structural biology ...
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