The action of lipases on chloroplast membranes. III. The effect of lipid hydrolysis on chlorophyll-protein complexes in thylakoid membranes

Bean thylakoid membranes treated with various lipolytic enzymes (bean galactolipase, phospholipases A₂, C, D) showed marked changes in their acyl lipid composition. As a consequence of acyl lipids hydrolysis, destruction of some chlorophyll a-protein complexes (CP1a, CP1, CPa) or monomerization of the oligomeric of light harvesting chlorophyll a/b protein complex (LHCP) was observed. It is concluded that galactolipids and phosphatidylcholine are responsible for the stability of CP1a, CP1 and CPa, respectively. Phosphatidylglycerol and to some extent monogalactosyldiacylglycerol are essential for the stabilization of oligomeric structures of light harvesting chlorophyll a/b protein complex.Abbreviations chl chlorophyll - CP1a, CP1 chl a-protein complexes, of PSI - CPa chl a-protein complex of PSII - DGDG diagalactosyldiacylglycerol - FC free chl - GL galactolipase - LHCP^1–3 light harvesting chl a/b protein complex - MGDG monogalactosyldiacylglycerol - PAGE polyacrylamide gel electrophoresis - PC phosphatidylcholine - PG phosphatidylglycerol - PLA₂ phospholipase A₂ - PL phospholipase C - PLD phospholipase D - PSI photosystem I - PSII photosystem II - SDS sodium dodecyl sulphate - SQDG sulfoquinovosyl-diacylglycerol - TCA trichloroacetic acid - Tricine N-tris-(hydroxymethyl)-methylglycine - Tris Tris-(hydroxymethyl)-aminomethan     

The reconstitution of energy transfer in membranes from a bacteriochlorophyll-less mutant of Rhodopseudomonas sphaeroides by addition of light-harvesting and reaction centre pigment-protein complexes

Antenna and reaction centre complexes purified from photosynthetically-grown cells of Rhodopseudomonas sphaeroides have been mixed with cytoplasmic membranes prepared from an aerobically-grown bacteriochlorophyll-less mutant of Rp. sphaeroides (designated 01) in the presence of 1% sodium cholate. After removal of the cholate by dialysis, the dialysate was subjected to isopycnic centrifugation. Reconstituted cytochrome c₂ photooxidation and cytochrome b photoreduction were demonstrated in a pigmented fraction recovered from the sucrose gradient, suggesting that the pigment-proteins were incorporated into the 01 membrane.

The fluorescence properties of the system were examined. The appearance of a variable component after the initial fast fluorescence rise indicated that energy transfer occurred between the antenna and reaction centre proteins in the presence of 01 membrane. The order in which the system was assembled was important. Reconstituted energy transfer with a pre-dialysed reaction centre-antenna complex was more effective than when all the components were mixed at once. Energy transfer was also reconstituted between added reaction centre protein and the endogenous antenna present in membranes from the pigmented, but aerobically-grown reaction centre-less mutant PM8dp of Rp. sphaeroides.

Preparations of 01 membranes reconstituted with reaction centre exhibited a light intensity dependent cytochrome c₂ photooxidation. At low exciting light intensities, preparations containing reconstituted antenna protein in addition to reaction centres showed greater membrane cytochrome c₂ photooxidation than preparations with the antenna omitted; this improvement was maximal when a pre-dialysed antenna-reaction centre complex was used.     

Effects of diquat on pigment-protein complexes of thylakoid membranes in soybean and maize plants

Soybean (Glycine max Merrill) and maize (Zea mays L.) plants were exposed for 5 to 48 h to the herbicide diquat under "white light" (WL) or far-red radiation (FR) (photon fluence rate of 30 μmol m^-2 s^-1). The WL enhanced diquat effect on chlorophyll content in soybean plants, while FR had the same effects on maize plants. After 5 h, diquat increased the content of polypeptides bound to light-harvesting proteins in both plants. This revised version was published online in July 2006 with corrections to the Cover Date.     

Excitation energy transfer in native and unstacked thylakoid membranes studied by low temperature and ultrafast fluorescence spectroscopy

In this work, the transfer of excitation energy was studied in native and cation-depletion induced, unstacked thylakoid membranes of spinach by steady-state and time-resolved fluorescence spectroscopy. Fluorescence emission spectra at 5 K show an increase in photosystem I (PSI) emission upon unstacking, which suggests an increase of its antenna size. Fluorescence excitation measurements at 77 K indicate that the increase of PSI emission upon unstacking is caused both by a direct spillover from the photosystem II (PSII) core antenna and by a functional association of light-harvesting complex II (LHCII) to PSI, which is most likely caused by the formation of LHCII-LHCI-PSI supercomplexes. Time-resolved fluorescence measurements, both at room temperature and at 77 K, reveal differences in the fluorescence decay kinetics of stacked and unstacked membranes. Energy transfer between LHCII and PSI is observed to take place within 25 ps at room temperature and within 38 ps at 77 K, consistent with the formation of LHCII-LHCI-PSI supercomplexes. At the 150–160 ps timescale, both energy transfer from LHCII to PSI as well as spillover from the core antenna of PSII to PSI is shown to occur at 77 K. At room temperature the spillover and energy transfer to PSI is less clear at the 150 ps timescale, because these processes compete with charge separation in the PSII reaction center, which also takes place at a timescale of about 150 ps.     

Carotenoid distribution and deepoxidation in thylakoid pigment-protein complexes from cotton leaves and bundle-sheath cells of maize

In response to excess light, the xanthophyll violaxanthin (V) is deepoxidized to zeaxanthin (Z) via antheraxanthin (A) and the degree of this deepoxidation is strongly correlated with dissipation of excess energy and photoprotection in PS II. However, little is known about the site of V deepoxidation and the localization of Z within the thylakoid membranes. To gain insight into this problem, thylakoids were isolated from cotton leaves and bundle-sheath strands of maize, the pigment protein-complexes separated on Deriphat gels, electroeluted, and the pigments analyzed by HPLC. In cotton thylakoids, 30% of the xanthophyll cycle pigments were associated with the PS I holocomplex, including the PS I light-harvesting complexes and PS I core complex proteins (CC I), and about 50% with the PS II light-harvesting complexes (LHC II). The Chl was evenly distributed between PS I and PS II. Less than 2% of the neoxanthin, about 18% of the lutein, and as much as 76% of the -carotene of the thylakoids were associated with PS I. Exposure of pre-darkened cotton leaves to a high photon flux density for 20 min prior to thylakoid isolation caused about one-half of the V to be converted to Z. The distribution of Z among the pigment-protein complexes was found to be similar to that of V. The distribution of the other carotenoids was unaffected by the light treatment. Similarly, in field-grown maize leaves and in the bundle-sheath strands isolated from them, about 40% of the V present at dawn had been converted to Z at solar noon. Light treatment of isolated bundle-sheath strands which initially contained little Z caused a similar degree of conversion of V to Z. As in cotton thylakoids, about 30% the V+A+Z pool in bundle-sheath thylakoids from maize was associated with the PS I holocomplex and the CC I bands and 46% with the LHC II bands, regardless of the extent of deepoxidation. These results demonstrate that Z is present in PS I as well as in PS II and that deepoxidation evidently takes place within the pigment-protein complexes of both photosystems.Abbreviations A antheraxanthin - CC I, CC II Core or reaction center complex of PS I, PS II - CP Chl protein - EPS epoxidation state - F_m Chl fluorescence at closed PS II reaction centers - IEF isoelectric focussing gels - LHC I, LHC II light-harvesting complex of PS I, PS II - OE oxygen evolving polypeptide - PFD photon flux density - PS I^* PS I holocomplex - V violaxanthin - Z zeaxanthin - antibody against C.I.W.-D.P.B. Publication No. 1127.     

The action of lipases on chloroplast membranes I. The release of plastocyanin from galactolipase-treated thylakoid membranes

Bean chloroplasts treated with galactolipase (lipolytic acyl hydrolase) isolated from bean leaves showed an inhibition of photosystem I activity as measured by methyl viologen-mediated oxygen uptake and NADP⁺ photoreduction. This inhibition was partially reversed by exogenous plastocyanin added to galactolipase-treated thylakoid membranes. Galactolipase released substantial amounts of endogenous plastocyanin (about 40%) from bean chloroplasts. The results are discussed with regard to the localization of plastocyanin in thylakoid membranes.Abbreviations chlf chlorophyll - DCMU 3-(2,4-dichlorophenyl)-1,1-dimethylurea - DGDG digalactosyldiacylglycerol - MGDG monogalactosyldiacylglycerol - MV methyl viologen - NADP⁺ nicotinamide dinucleotide phosphate - PC phosphatidylcholine - PG phosphatidylglycerol - PE phosphatidylethanolamine - PI phosphatidylinositol - SQDG sulphoquinovosyldiacylglycerol - SDS sodium dodecyl sulphate - TMPD N,N,N,N-tetramethyl-p-phenylenediamine - Tricine N-Tris-(hydroxymethyl)-methylglycine - Tris Tris-(hydroxymethyl)-aminomethane     

Excitation energy transfer in thylakoid membranes from Chlamydomonas reinhardtii lacking chlorophyll b and with mutant Photosystem I

Energy trapping in Photosystem I (PS I) was studied by time-resolved fluorescence spectroscopy of PS II-deleted Chl b-minus thylakoid membranes isolated from site-directed mutants of Chlamydomonas reinhardtii with specific amino acid substitutions of a histidine ligand to P₇₀₀. In vivo the fluorescence of the PS I core antenna in mutant thylakoids with His-656 of PsaB replaced by asparagine, serine or phenylalanine is characterized by an increase in the lifetime of the fast decay component ascribed to the energy trapping in PS I (25 ps in wild type PS I with intact histidine-656, 50 ps in the mutant PS I with asparagine-656 and 70 ps in the mutant PS I with phenylalanine-656). Assuming that the excitation dynamics in the PS I antenna are trap-limited, the increase in the trapping time suggests a decrease in the primary charge separation rate. Western blot analysis showed that the mutants accumulate significantly less PS I than wild type. Spectroscopically, the mutations lead to a decrease in relative quantum yield of the trapping in the PS I core and increase in relative quantum yield of the fluorescence decay phase ascribed to uncoupled chlorophyll–protein complexes which suggests that improper assembly of PS I and LHC in the mutant thylakoids may result in energy uncoupling in PS I.     

Alteration of thylakoid membrane structure in Brassica rapa ssp. oleifera during ageing in high and low light

Abstract Alterations in the composition and structure of thylakoids were studied in Brassica rapa ssp. oleifera grown under high and low irradiance (800 μmol m^?2 s^?1 and 80 μmol m^?2 s^?1). During ageing, both high and low light induced a decrease in total protein particle density and in the relative amount of 80–90 Å cytochrome b6/f and 90–100 Å ATP-synthetase. The density of PSII complexes in stacked (EFs) and unstacked (EFu) thylakoids also decreased. In high light, a shift was noted towards smaller PSII complexes in the EFs face with decreasing attached antenna complex CP29, but the relative amount of the antenna chlorophyll a-protein complexes of photosystem II (CPa) remained stable. In contrast, the proportion of peripheral LHCH on the PFs face and the density of PFs particles increased together with an increase in grana size. In low light, a shift occurred towards larger PSII complexes on the EFs face, along with a decrease in the proportion of CPa complexes and the PFs particle density (peripheral LHCH), though a marked increase was observed in the proportion of chlorophyll a/b-protein complexes in SDS-PAGE. The amount of photosystem I in green gel remained fairly stable, although the density of PFu particles (including PSI) increased in low and slightly diminished in high light. The results indicate that the organization of thylakoid components depends strongly on the light conditions and stage of development.     

On-line preparation of peroxymonocarbonate and its application for the study of energy transfer chemiluminescence to lanthanide inorganic coordinate complexes.

It has been shown that peroxymonocarbonate ion (HCO(4) (-)) is a potent oxidant. In this study, a flow-injection system was developed in order to prepare on-line HCO(4) (-) ion and the optimum conditions for the on-line preparation of HCO(4) (-) were studied in detail. We used 99% (13)C-enriched NaHCO(3) to examine peroxymonocarbonate by (13)C-NMR at 25 degrees C. An ultra-weak chemiluminescence (CL) was observed after mixing H(2)O(2) and sodium bicarbonate in an organic co-solvent that can accelerate the formation of HCO(4) (-) ion. When lanthanide inorganic coordinate complex, Eu(II)-EDTA, was added into this HCO(4) (-) system, the CL intensity was significantly enhanced. The CL mechanism was investigated by various methods. The experimental results indicate that peroxymonocarbonate oxidizes Eu(II) to Eu(III) and produces singlet oxygen; meanwhile, the energy originating from dimers of singlet oxygen is accepted by the Eu(III)-EDTA(-) complex. The excited Eu(III) ions undergo radiative deactivation and emit CL.     

The reconstitution of energy transfer in membranes from a bacteriochlorophyll-less mutant of Rhodopseudomonas sphaeroides by addition of light-harvesting and reaction centre pigment-protein complexes.

Antenna and reaction centre complexes purified from photosynthetically-grown cells of Rhodopseudomonas sphaeroides have been mixed with cytoplasmic membranes prepared from an aerobically-grown bacteriochlorophyll-less mutant of Rp. sphaeroides (designated 01) in the presence of 1% sodium cholate. After removal of the cholate by dislysis, the dislysate was subjected to isopycnic centrifugation. Reconstituted cytochrome c2 photooxidation and cytochrome b photoreduction was demonstrated in a pigmented fraction recovered from the sucrose gradient, suggesting that the pigment-proteins were incorporated into the 01 membrane. The fluorescence properties of the system were examined. The appearance of a variable component after the initial fast fluorescence rise indicated that energy transfer occurred between the antenna and reaction centre proteins in the presence of 01 membrane. The order in which the system was assembled was important. Reconstituted energy transfer with a pre-dialysed reaction centre-antenna complex was more effective than when all the components were mixed at once. Energy transfer was also reconstituted between added reaction centre protein and the endogenous antenna present in membranes from the pigmented, but aerobically-grown reaction centre-less mutant PM8dp of Rp. sphaeroides. Preparations of 01 membranes reconstituted with reaction centre exhibited a light intensity dependent cytochrome c2 photooxidation. At low exciting light intensities, preparations containing reconstituted antenna protein in addition to reaction centres showed greated membrane cytochrome c2 photooxidation than preparations with the antenna omitted; this improvement was maximal when a pre-dialysed antenna-reaction centre complex was used.     

Generation and spectroscopic characterization of new 18+δ electron complexes. Relationship between the stability of 18+δ electron organometallic complexes and their ligand reduction potentials

The relationship between the electrochemical reduction potential of a ligand and the ability of that ligand to form a kinetically inert 18+δ complex in a reaction with a 17-electron radical was investigated. (18+δ complexes are 19-electron adducts in which the unpaired electron is primarily located on a ligand orbital.) To probe the relationship, a series of 18+δ complexes was generated by irradiating the Cp′₂Mo₂(CO)₆, Cp₂Fe₂(CO)₄ and Co₂(CO)₈ dimers in the presence of a series of bidentate phosphorus ligands. (Irradiation of the dimers formed 17-electron metal radicals by photolysis of the metal-metal bonds.) These experiments showed that bidentate phosphorus ligands with reduction potentials more positive than −1 volt (versus SCE) formed long-lived 18+δ complexes (in THF or CH₂Cl₂ solutions at 23 °C), while ligands with potentials more negative than −1 V formed reactive 18+δ complexes. The inability to detect 18+δ complexes in the latter case is attributed to kinetic factors: the 18+δ complexes are powerful reductants and they readily initiate a chain disproportionation of the dimers by electron transfer. Analogous experiments with bidentate nitrogen ligands did not produce any detectable 18+δ complexes. In this case, the undetectability of the 18+δ complexes is probably thermodynamic in origin: the hard nitrogen ligands and soft metal centers form adducts that are unstable with respect to metal-nitrogen bond cleavage. 18+δ complexes are the subject of increasing interest, especially as models for their more reactive 19-electron-complex counterparts. These results provide some guidelines for the design of 18+δ complexes that can be synthesized, isolated and characterized for such studies.     

A structural basis of light energy and electron transfer in biology

Aspects of intramolecular light energy and electron transfer will be discussed for three protein cofactor complexes, whose three-dimensional structures have been elucidated by x-ray crystallography: Components of light harvesting cyanobacterial phycobilisomes, the purple bacterial reaction centre, and the blue multi-copper oxidases. A wealth of functional data is available for these systems which allow specific correlations between structure and function and general conclusions about light energy and electron transfer in biological materials to be made.     

Correlation between persistent forms of zeaxanthin-dependent energy dissipation and thylakoid protein phosphorylation

High light stress induced not only a sustained form of xanthophyll cycle-dependent energy dissipation but also sustained thylakoid protein phosphorylation. The effect of protein phosphatase inhibitors (fluoride and molybdate ions) on recovery from a 1-h exposure to a high PFD was examined in leaf discs of Parthenocissus quinquefolia (Virginia creeper). Inhibition of protein dephosphorylation induced zeaxanthin retention and sustained energy dissipation (NPQ) upon return to low PFD for recovery, but had no significant effects on pigment and Chl fluorescence characteristics under high light exposure. In addition, whole plants of Monstera deliciosa and spinach grown at low to moderate PFDs were transferred to high PFDs, and thylakoid protein phosphorylation pattern (assessed with anti-phosphothreonine antibody) as well as pigment and Chl fluorescence characteristics were examined over several days. A correlation was obtained between dark-sustained D1/D2 phosphorylation and dark-sustained zeaxanthin retention and maintenance of PS II in a state primed for energy dissipation in both species. The degree of these dark-sustained phenomena was more pronounced in M. deliciosa compared with spinach. Moreover, M. deliciosa but not spinach plants showed unusual phosphorylation patterns of Lhcb proteins with pronounced dark-sustained Lhcb phosphorylation even under low PFD growth conditions. Subsequent to the transfer to a high PFD, dark-sustained Lhcb protein phosphorylation was further enhanced. Thus, phosphorylation patterns of D1/D2 and Lhcb proteins differed from each other as well as among plant species. The results presented here suggest an association between dark-sustained D1/D2 phosphorylation and sustained retention of zeaxanthin and energy dissipation (NPQ) in light-stressed, and particularly photoinhibited, leaves. Functional implications of these observations are discussed.This revised version was published online in October 2005 with corrections to the Cover Date.     

Freezing of isolated thylakoid membranes in complex media. V. Inactivation and protection of electron transport reactions

When chloroplast thylakoid membranes isolated from spinach leaves (Spinacia oleracea L. cv. Monatol) were frozen in media containing the predominant inorganic electrolytes of the chloroplast stroma, linear photosynthetic electron transport became progressively inhibited. After onset of freezing, both PSII- and PSI-mediated electron flow were inactivated almost to the same extent. Prolonged storage of the membranes in the frozen state increased damage to PSII relative to PSI activity. Under these conditions, a preferential injury of the water oxidation system was not observed. In thylakoids stored at 0 °C, PSI activity remained fairly unimpaired but inactivation of PSII occurred with strongest inhibition at the oxidizing side.The addition of low-molecular-weight cryoprotectants such as glycerol, sugars, certain amino acids and carbonic acids to thylakoid suspensions prior to freezing provided almost complete preservation of PSI activity and considerable but incomplete stabilization of PSII.Abbreviations BQ 1,4-benzoquinone - Chl chlorophyll - DAD 1,4-diamino-2,3,5,6-tetramethylbenzene - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - DCPIP 2,6-dichlorophenolindophenol - DMBQ 2,5-dimethyl-p-benzoquinone - DPC 1,5-diphenylcarbazide - Hepes 4-(2-hydroxyethyl)-1-piperazineeth-anesulfonic acid - MV methylviologen - PD 1,4-diaminobenzene - SOD superoxide dismutase (EC 1.15.1.1) - TMHQ tetramethyl-p-hydroquinone - TMPD N,N,N,N-tetramethyl-1,4-diaminobenzene - Tris 2-amino-2-(hydroxymethyl)-1,3-propandiol Dedicated to Professor Dr. Wilhelm Simonis, Würzburg, on the occasion of his 80th birthday     

Effects of protein-protein interactions on electron transfer: docking and electron transfer calculations for complexes between flavodoxin and c-type cytochromes

 Theoretical studies of protein-protein association and electron transfer were performed on the binary systems formed by Desulfovibrio vulgaris Hildenborough (D. v. H.) flavodoxin and D. v. H. cytochrome c ₅₅₃ and by flavodoxin and horse heart cytochrome c. Initial structures for the complexes were obtained by rigid-body docking and were refined by MD to allow for molecular flexibility. The structures thus obtained were analysed in terms of their relative stability through the calculation of excess energies. Electrostatic, van der Waals and solvation energy terms showed all to have significant contributions to the stability of complexes. In the best association solutions found for both cytochromes, these bind to different zones of flavodoxin. The binding site of flavodoxin observed for cytochrome c is in accordance with earlier works [27]. The various association modes found were characterised in terms of electron transfer using the Pathways model. For complexes between flavodoxin and horse heart cytochrome c, some correlation was observed between electron tunnelling coupling factors and conformation energy; the best conformation found for electron transfer corresponded also to the best one in terms of energy. For complexes between flavodoxin and cytochrome c ₅₅₃ this was not the case and a lower correlation was observed between electron tunnelling coupling factors and excess energies. These results are in accordance with the differences in the experimental dependence of electron transfer rates with ionic strength observed between these two cases. Received: 29 December 1998 / Accepted: 22 March 1999     

Functional and structural organization of chlorophyll in the developing photosynthetic membranes of Euglena gracilis Z. V-separation and characterization of pigment-protein complexes of the differentiated thylakoids

Low temperature sodium dodecyl sulfate polyacrylamide gel electrophoresis following mild solubilization of Euglena thylakoid components allowed to resolve, in addition to the main CP1, CPa and LHCP chlorophyll-protein complexes, the additional CP1a and LHCP green bands. A carotenoid enriched band CPc can be separated from CPa using high acrylamide concentration. Pigment and polypeptide composition of these complexes were analyzed by absorption and fluorescence measurements and two dimensional gel electrophoresis. Spectral properties of CP1 and CP1a indicate an heterogenous organization of chlorophyll and the presence of significant amount of chlorophyll b in these complexes. They both contain a major 68 kilodalton polypeptide associated with three minor low molecular weight polypeptides in CP1a. CPa and CPc exhibit a characteristic fluorescence emission at 687 nm and they each contain one polypeptide of 54 and 41 Kda respectively. LHCP and LHCP are less abundant than in higher plant thylakoids and they contain a lower proportion of chl b (chl a: chl b=3). They include two polypeptides of 26 and 29 Kda.Abbreviations chl chlorophyll - SDS Sodium Dodecyl Sulfate - EDTA Ethylene Diamine Tetraacetic Acid - DTT Dithiothreitol     

The fluidity of chloroplast thylakoid membranes and their constituent lipids: A comparative study by ESR

Comparative measurements were made of the fluidity of chloroplast thylakoids, total membrane lipids and polar lipids utilizing the order parameter and motion of spin labels.No significant differences were found in the fluidity of membranes or total membrane lipids from a wild type and a mutant barley (Hordeum vulgare chlorina f₂ mutant) which lacks chlorophyll $\text{b}$ and a 25 000 dalton thylakoid polypeptide. Redistribution of intrinsic, exoplasmic face (EF) membrane particles by unstacking thylakoid membranes in low salt medium also had no effect on membrane fluidity. However, heating of isolated thylakoids decreased membrane fluidity.The fluidity of vesicles composed of membrane lipids is much greater than that of the corresponding membranes. Fluidity of the membranes, however, increased during greening indicating that the rigidity of the membranes, compared with that of total membrane lipids, is not caused by chlorophyll or its associated peptides. It is concluded that the restriction of motion in the acyl chains in the thylakoids is not caused by chlorophyll or the major intrinsic polypeptide but by some other protein components.     

Reactivity difference between protolytic forms of some macrocyclic chromium(III) complexes in ligand substitution and electron transfer processes

The review provides insight into the mechanism of ligand substitution and electron transfer (from chromium(III) to iron(III)) by comparison of the reactivity of some tetraazamacrocyclic chromium(III) complexes in the conjugate acid-base forms. Use of two geometrical isomers made possible to estimate the influence of geometry and protolytic reactions in trans and cis position towards the leaving group on the rate enhancement. Studies on the reaction rates in different media demonstrated the role played by outer sphere interactions in a monodentate ligand substitution.     

Chemiluminescence and energy transfer mechanism of lanthanide ions in different media based on peroxomonosulfate system

The chemiluminescence (CL) phenomena of lanthanide (Ln) ions and their coordinate complexes in peroxomonosulfate system and the energy transfer mechanism during the process were investigated in this work. A strong and sharp CL signal was yielded when the Eu(III) or Tb(III) solution was added to the peroxymonosulfate solution. The CL intensity was greatly enhanced by 2,6‐pyridinedicarboxylic acid (DPA) ligand [maximum enhancement reached when Ln(III):DPA was 1:1] and hexadecyltrimethylammonium chloride micelles. The degree of enhancement of DPA and micelles on Ln(III) CL was related to the fluorescence lifetimes of Ln(III) in different media. According to the ESR spin‐trapping experiments of 2,2,6,6‐tetramethyl‐4‐piperidone and the specific quenching experiments of 1,4‐diazabicyclo[2.2.2]octane and sodium azide, singlet oxygen was generated though the Ln(III) ion‐catalyzed decomposition of peroxymonosulfate. From the comparisons of the fluorescence and CL spectra, lanthanide ions were the luminescence emitter and the ligand DPA absorbed the energy from singlet oxygen and transferred it to Ln(III) ions in the coordinate complexes. Micelles can enhance the CL intensity by improving intermolecular energy transfer efficiencies, removing the quenching effect of water and prolonging the lifetime of singlet oxygen. Copyright © 2009 John Wiley & Sons, Ltd.