DOCSLIB.ORG

Primary Charge Separation in Bacterial Photosynthesis: Oxidized Chlorophylls and Reduced Pheophytin (Reduced Bacteriopheophytin/Transient Electron Acceptor) J

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Primary Charge Separation in Bacterial Photosynthesis: Oxidized Chlorophylls and Reduced Pheophytin (Reduced Bacteriopheophytin/Transient Electron Acceptor) J Proc. Nat. Acad. Sci. USA Vol. 72, No. 12, pp. 4956-4960, December 1975 Biophysics Primary charge separation in bacterial photosynthesis: Oxidized chlorophylls and reduced pheophytin (reduced bacteriopheophytin/transient electron acceptor) J. FAJER, D. C. BRUNE, M. S. DAVIS, A. FORMAN, AND L. D. SPAULDING Department of Applied Science and Medical Research Center, Brookhaven National Laboratory, Upton, New York 11973 Communicated by Cerhart Friedlander, October 2, 1975 ABSTRACT Bacteriopheophytin, the magesium-free ubiquinone (UQ) from Rhodopseudomonas spheroides reac- base of bacteriochlorophyll, undergoes reversible one-elec- tion centers inhibits photochemical activity (8). To reconcile tron reduction in organic solvents to yield an anionic free the UQ data with ESR evidence of an iron compound, a radical with characteristic optical and electron spin reso- nance spectra. The reduction potential of bacteriopheophy- complex of iron-ubiquinone (Fe-UQ), Em = -50 mv, is tin, E1/2 ;-0.55 V against a normal hydrogen electrode, generally considered to be a primary electron acceptor (9- compared to E1/2 t-0.85 V for bacteriochlorophyll, renders 11). itoalikely electron acceptor in the rimary charge separation Recent nanosecond and picosecond laser excitations of R. of photosynthesis. Comparison of these data with picosecond spheroides reaction centers, poised at potentials where optical changes recently observed upon pulsed laser excita- transient state, pF, which tion of bacterial reaction centers leads us to propose that X(Fe-UQ) is reduced, reveal a bacteriopheophytin is indeed a transient electron acceptor forms with high quantum yield. pF exhibits optical changes and that the primary charge separation of bacterial photo- that implicate both BChl and BPh and decays with an expo- synthesis occurs between the bacteriochlorophyll complex nential time r = 150-250 psec with the concomitant appear- P870 and bacteriopheophytin to yield the radicals of the oxi- ance of P+870X- when X is not initially reduced. Strikingly, dized chlorophyll dimer cation and reduced pheophytin P870 oxidation seems to occur with X reduced as well (12- anion. 15). We present here evidence that equates pF with the pri- Light is converted by green plants and photosynthetic bacte- mary charge separation of bacterial photosynthesis and pro- ria into chemical energy by the creation of an oxidant (P+) pose that bacteriopheophytin is the transient electron accep- and a reductant (X-) which result from ejection of an elec- tor of the P870 oxidation. tron from (bacterio)chlorophyll (P) to a nearby acceptor (X). An extensive body of evidence (for reviews, see refs. 1-5) EXPERIMENTAL leads to the conclusion that light impinging on a photosyn- Cyclic voltammetry, controlled potential electrolysis, and thetic organism is gathered by antenna chlorophylls (and coulometry were performed using a Princeton Applied Re- other pigments) and funneled to a special environment, the search potentiostat 173 equipped with a function generator reaction center, wherein a chlorophyll "special pair" (P7oo in 175 and a digital coulometer 179. Potentials were deter- plants and P870 in purple bacteria) undergoes one electron mined on 1o-3 M solutions containing 0.1 M tetrapropylam- oxidation to yield a ir cation radical [P7oo+ and P870+ (5)] monium perchlorate against an aqueous saturated calomel with characteristic optical, electron spin resonance (ESR), electrode (= NHE -0.24 V). Optical spectra were obtained electron-nuclear double resonance, and redox properties. with a vacuum electrolysis cell on a Cary 17 spectrophotom- Isolation of photochemically active reaction centers of pur- eter. The optical data used for the difference spectra of Figs. ple bacteria simplifies the study of the charge separation 3 and 4 were digitized using a Vanguard scanner and pro- since each reaction center contains only three different poly- cessed on a Control Data Corp. 6600 computer. ESR spectra peptides (about 70,000 daltons), four bacteriochlorophylls, were collected at X-band on a Varian E-12 spectrometer, two bacteriopheophytins, one ubiquinone, and a nonheme equipped with a Field/Frequency Lock accessory and iron, and is free of cytochromes, copper, and antenna bac- ramped by an SDS Sigma 2 computer. All ESR and optical teriochlorophyll. Circular dichroism (CD) spectra indicate spectra were obtained on samples prepared on a vacuum that, within the reaction center, the bacteriochlorophylls line using dried, distilled, and outgassed solvents with oxy- (BChls) are strongly exciton coupled, with weaker interac- gen rigorously excluded. The chemical and electrochemical tions with the bacteriopheophytins (BPhs). The creation of techniques have been described (16-18). A Coherent Radia- P+870, on oxidation of the reaction center, disrupts the CD tion krypton ion laser and a quartz halogen Oriel lamp were interactions and the orientation of the pigment molecules is used for the photochemical reductions. BPh a was prepared disturbed (1-3). from BChl a extracted from Chromatium vinosum [BChls The nature of the electron acceptor (X) is less clear (1-4). found in C. mnosum and R. spheroides have the same Midpoint potentials, Em, for the one electron reduction of X chemical composition (19)]. BPh was dissolved in CH2Cl2, in different species of bacteria range between 0 and -150 which was pumped away to codistill water, and the pigment mv [against a normal hydrogen electrode (NHE)], but values was dried under reduced pressure (10-3 Pa) for several as low as -350 mv have been reported (2, 6, 7). Removal of hours. Abbreviations: BPh, bacteriopheophytin; BPh-, reduced BPh; BChl, bacteriochlorophyll; ESR, electron spin resonance; E1/2, half RESULTS wave potential; Em, midpoint potential; P870, BChl special pair with The anion radical of bacteriopheophytin 870 nm absorbance; P*870, excited singlet of P870; P+870, oxidized P870; NHE, normal hydrogen electrode; UQ, ubiquinone; X, elec- BPh exhibits a reversible, one electron, halfwave reduction tron acceptor, iron-ubiquinone complex. potential E1/2 of -0.58 against NHE in CH2Cl2. Electro- 4956 Downloaded by guest on October 2, 2021 Biophysics: Fajer et al. Proc. Nat. Acad. Sci. USA 72 (1975) 4957 BPh- CH2Cl2 It deriv (0) ; .,C ;,X !~~r :C( / S9>O\2' CH2CI2 )O 700 800 900 1000 X nm 10 G FIG. 1. Optical spectra of BPh --- -) and of the anion radical FIG. 2. (a) First and (b) second derivative ESR spectra of BPh - in BPh- in CH2Cl2, (c) second derivative spectrum of BPh- in pyri- (-) CH2Cl2. dine, and (d) computer simulation of (c) using the splitting con- stants shown. chemical reduction requires one electron and yields the opti- cal spectra shown in Fig. 1. One electron oxidation regener- field molecular orbital calculations by Feltont. Thus, posi- ates better than 95% of the original BPh. The system can be tions 1, 2, 5, 6, 6, a, and 3 each carry about 0.1 unit of un- recycled to again yield the radical spectrum. The ESR spec- paired spin while the spin density in rings II and IV is con- trum of BPh- in CH2Cl2 at room temperature exhibits a g- centrated in the nitrogens. value of 2.0030 (+0.0002) and a 12 line, partially resolved The good agreement with model systems and molecular hyperfine structure (Fig. 2)*. Similar spectra, with only orbital calculations minimizes the possibility that the species minor variations in apparent splitting constants and line- observed is the result of a proton addition: BPh- + H+ - widths are obtained by chemical reduction with an 18- BPhH.. Molecular orbital calculations for BPhH- indicate crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane) ether/po- that large spin densities would exist at the site adjacent to tassium complex in 2-methyltetrahydrofuran (20, 21) and by the proton addition (presumably one of the meso positions) photochemical reduction in pyridine in the presence of Na2S and would result in large couplings with the added protont. (22). We observe no initial difference in the ESR spectrum of The ESR spectrum in pyridine is displayed for compari- BPh- prepared photochemically in pyridine that contains son with a computer simulation (Fig. 2). The simulation as- small amounts of H20 or D20* (the radical eventually under- sumes interaction of the unpaired electron spin density with goes isotopic exchange, not addition) and conversely, we de- the following nuclei: (a) 2 nitrogens (rings II and IV) with tect no difference in the ESR spectra of perdeutero BPh- in hyperfine splitting constant aN = 2.3 G (2.3 X 10-4 tesla), perdeutero pyridine containing D20 or H20. (b) 3 protons, average aH = 2.5 G for the hydrogens of posi- In conclusion, we find an anion radical of BPh stable in tion 6, a, and f3, and (c) 6 protons, average aHCH, = 3.0 G several solvents with a halfwave reduction potential which for the methyl groups 1 and 5 on rings I and III, respective- varies slightly from solvent to solvent: EI/2 (against NHE) = ly. These assignments are deduced from ESR and electron- -0.58 V in CH2CI2, -0.54 in butyronitrile, -0.51 in di- nuclear double resonance observations on BPh-, deuterated methylformamide, and -0.52 in ethanol [pH = 9.4 (23)] for BPh-, and selectively deuterated BPh- t. In addition, they an averaged EI/2 -0.55 V. These compare with EI/2 are in accord with the ESR spectra of the anion radical of a values of +0.64 and -0.86 V for oxidation and reduction of model compound, free base tetraphenyl bacteriochlorin, also BChl in CH2C12. selectively deuterated, and all the above ESR data are in A biological role for bacteriopheophytin general agreement with Pariser, Parr, Pople self-consistent- We now propose that, in bacterial reaction centers, bacterio- pheophytin acts as a transient electron acceptor on a picosec- * The spectrum collapses to a singlet, AHptp = 13 G at 100 K. ond time scale and that the electron donor is the P870 special t The different nuclear spin of deuterium, I = 1 compared with I = pair.
Load more

Recommended publications
  • Influence of Alkaline Treatment on Structural Modifications Of
    foods Article Influence of Alkaline Treatment on Structural Modifications of Chlorophyll Pigments in NaOH—Treated Table Olives Preserved without Fermentation Marta Berlanga-Del Pozo, Lourdes Gallardo-Guerrero and Beatriz Gandul-Rojas * Chemistry and Biochemistry of Pigments, Food Phytochemistry, Instituto de la Grasa (CSIC), Campus Universitario Pablo de Olavide, Edificio 46, Ctra. Utrera km 1, 41013 Sevilla, Spain; [email protected] (M.B.-D.P.); [email protected] (L.G.-G.) * Correspondence: [email protected] Received: 28 April 2020; Accepted: 18 May 2020; Published: 1 June 2020 Abstract: Alkaline treatment is a key stage in the production of green table olives and its main aim is rapid debittering of the fruit. Its action is complex, with structural changes in both the skin and the pulp, and loss of bioactive components in addition to the bitter glycoside oleuropein. One of the components seriously affected are chlorophylls, which are located mainly in the skin of the fresh fruit. Chlorophyll pigments are responsible for the highly-valued green color typical of table olive specialties not preserved by fermentation. Subsequently, the effect on chlorophylls of nine processes, differentiated by NaOH concentration and/or treatment time, after one year of fruit preservation under refrigeration conditions, was investigated. A direct relationship was found between the intensity of the alkali treatment and the degree of chlorophyll degradation, with losses of more than 60% being recorded when NaOH concentration of 4% or greater were used. Oxidation with opening of the isocyclic ring was the main structural change, followed by pheophytinization and degradation to colorless products. To a lesser extent, decarbomethoxylation and dephytylation reactions were detected.
    [Show full text]
  • Chapter 3 the Title and Subtitle of This Chapter Convey a Dual Meaning
    3.1. Introduction Chapter 3 The title and subtitle of this chapter convey a dual meaning. At first reading, the subtitle Photosynthetic Reaction might seem to indicate that the topic of the structure, function and organization of Centers: photosynthetic reaction centers is So little time, so much to do exceedingly complex and that there is simply insufficient time or space in this brief article to cover the details. While this is John H. Golbeck certainly the case, the subtitle is Department of Biochemistry additionally meant to convey the idea that there is precious little time after the and absorption of a photon to accomplish the Molecular Biology task of preserving the energy in the form of The Pennsylvania State University stable charge separation. University Park, PA 16802 USA The difficulty is there exists a fundamental physical limitation in the amount of time available so that a photochemically induced excited state can be utilized before the energy is invariably wasted. Indeed, the entire design philosophy of biological reaction centers is centered on overcoming this physical, rather than chemical or biological, limitation. In this chapter, I will outline the problem of conserving the free energy of light-induced charge separation by focusing on the following topics: 3.2. Definition of the problem: the need to stabilize a charge-separated state. 3.3. The bacterial reaction center: how the cofactors and proteins cope with this problem in a model system. 3.4. Review of Marcus theory: what governs the rate of electron transfer in proteins? 3.5. Photosystem II: a variation on a theme of the bacterial reaction center.
    [Show full text]
  • Chlorophyll and Pheophytin
    Application Note: Chlorophyll and Pheophytin INTRODUCTION Chlorophyll, the photosynthetic pigment in all plants, is a fluorescent molecule, thus it can be determined by fluorometry. Fluorometric techniques are now well established for both qualitative and quantitative measurement of the chlorophylls and pheophytins. For many applications, they have replaced the traditional spectrophotometric methods and have made analysis in the field practical. ADVANTAGES Fluorometric methods have many advantages over other methods. As one author stated, "Chlorophyll a was selected because... it is the only index of phytoplankton abundance presently available that can be measured by a continuous in-situ technique..."(1). According to another researcher, "The relative simplicity of these techniques enables much information to be rapidly gathered..." (2). A comparison study conducted by the U.S. Environmental Protection Agency has shown that fluorometric methods compare favorably with spectrophotometric results (3). Fluorometry has the following advantages over spectrophotometry: Sensitivity: Fluorometry is at least 1,000 times more sensitive than the spectrophotometric techniques (4 ,5). Up to 10 liters of water may be required for a single spectrophotometric chlorophyll determination (6, p. 186), but the fluorometer can obtain the same data from samples of 500 ml or less. Sometimes the large volumes required for spectrophotometric determination are nearly impossible to filter because of clogging problems. The spectrophotometric determination of chlorophyll involves filtration, disruption of the cells, and extraction of the chlorophyll, followed by absorbance measurements. The same extraction technique can be used to produce samples for fluorometric determination, with the advantage of greater sensitivity and thus smaller sample requirements. Speed: With a spectrophotometer, one must measure absorbance at several wavelengths (4, 6, p.
    [Show full text]
  • Chlorophyll Biosynthesis
    Chlorophyll Biosynthesis: Various Chlorophyllides as Exogenous Substrates for Chlorophyll Synthetase Jürgen Benz and Wolfhart Rüdiger Botanisches Institut, Universität München, Menziger Str. 67, D-8000 München 19 Z. Naturforsch. 36 c, 51 -5 7 (1981); received October 10, 1980 Dedicated to Professor Dr. H. Merxmüller on the Occasion of His 60th Birthday Chlorophyllides a and b, Protochlorophyllide, Bacteriochlorophyllide a, 3-Acetyl-3-devinylchlo- rophyllide a, Pyrochlorophyllide a, Pheophorbide a The esterification of various chlorophyllides with geranylgeranyl diphosphate was investigated as catalyzed by the enzyme chlorophyll synthetase. The enzyme source was an etioplast membrane fraction from etiolated oat seedlings ( Avena sativa L.). The following chlorophyllides were prepared from the corresponding chlorophylls by the chlorophyllase reaction: chlorophyllide a (2) and b (4), bacteriochlorophyllide a (5), 3-acetyl-3-devinylchlorophyllide a (6), and pyro­ chlorophyllide a (7). The substrates were solubilized with cholate which reproducibly reduced the activity of chlorophyll synthetase by 40-50%. It was found that the following compounds were good substrates for chlorophyll synthetase: chlorophyllide a and b, 3-acetyl-3-devinylchloro- phyllide a, and pyrochlorophyllide a. Only a poor or no reaction was found with protochloro­ phyllide, pheophorbide a, and bacteriochlorophyllide. This difference of reactivity was not due to distribution differences of the substrates between solution and pelletable membrane fraction. Furthermore, no interference between good and poor substrate was detected. Structural features necessary for chlorophyll synthetase substrates were discussed. Introduction Therefore no exogenous 2 was applied. The only substrate was 2 formed by photoconversion of endo­ The last steps of chlorophyll a (Chi a) biosynthe­ genous Protochlide (1) in the etioplast membrane.
    [Show full text]
  • Carotene Contents of Isolated Photosystem II Reaction Center Complexes
    Photosynthesis Research 52: 69±73, 1997. 69 c 1997 Kluwer Academic Publishers. Printed in the Netherlands. Technical communication A routine method to determine the chlorophyll a, pheophytin a and -carotene contents of isolated Photosystem II reaction center complexes Camiel Eijckelhoff & Jan P. Dekker Department of Physics and Astronomy, Institute of Molecular Biological Sciences, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands; Author for correspondence Received 13 February 1997; accepted in revised form 28 March 1997 Key words: chlorophyll, pheophytin, Photosystem II, reaction center Abstract The most simple way in which the stoichiometry of chlorophyll a, pheophytin a and -carotene in isolated Photosystem II reaction center complexes can be determined is by analysis of the spectrum of the extracted pigments in 80% acetone. We present two different calculation methods using the extinction coef®cients of the puri®ed pigments in 80% acetone at different wavelengths. One of these methods also accounts for the possible presence of chlorophyll b. The results are compared with results obtained with HPLC pigment analysis, and indicate that these methods are suitable for routine determination of the pigment stoichiometry of isolated Photosystem II reaction center complexes. Abbreviations: Car ± carotene; Chl ± chlorophyll; HPLC ± high-performance liquid chromatography; Pheo ± pheophytin; PS ± Photosystem; RC ± reaction center Introduction content of the PS II RC complex, since the number and energies of bound chlorophylls seriously affect the The smallest unit of Photosystem II (PS II) capable of interpretations of functional studies of the PS II reac- primary charge separation is the D1±D2-cytochrome tion center, such as those on the primary energy and b-559 reaction center complex (Nanba and Satoh electron transfer reactions (van Gorkom 1995).
    [Show full text]
  • Theoretical Study of the Excited States of Chlorin, Bacteriochlorin, Pheophytin A, and Chlorophyll a by the SAC/SAC-CI Method
    1320 J. Phys. Chem. B 1998, 102, 1320-1326 Theoretical Study of the Excited States of Chlorin, Bacteriochlorin, Pheophytin a, and Chlorophyll a by the SAC/SAC-CI Method J. Hasegawa, Y. Ozeki, K. Ohkawa, M. Hada, and H. Nakatsuji*,† Department of Synthetic and Biological Chemistry, Faculty of Engineering, Kyoto UniVersity, Sakyo-ku, Kyoto 606-01, Japan ReceiVed: September 4, 1997; In Final Form: NoVember 19, 1997 Excited states of free base chlorin (FBC), free base Bacteriochlorin (FBBC), pheophytin a (Pheo a), and chlorophyll a (Chlo a), which are derivatives of free base porphine (FBP), were calculated by the SAC (symmetry adapted cluster)/SAC-CI (configuration interaction) method. The results reproduced well the experimentally determined excitation energies. The reduction of the outer double bonds in the porphine ring in the order of FBP, FBC, and FBBC causes a breakdown of the symmetry and a narrowing of the HOMO- LUMO gap, which result in a red shift of the Qx band and an increase of its intensity. In the change from Pheo a to Chlo a, the Mg coordination reduces the quasidegeneracy in the Qx state and then increases the spectral intensity. The disappearance of the Qy humps from the absorption spectrum of Pheo a, compared with that of Chlo a, is due to the red shift of the Qy state. Introduction Many biological systems contain porphyrins, chlorins, and bacteriochlorins.1,2 These compounds often take an important part in biochemical reactions, such as light absorption, electron transfer,1 and oxygen transport and storage.2 Because of their scientific importance, they have been the subject of a wide variety of studies.
    [Show full text]
  • EPR Studies of Photosystem II
    % !" #$%&!$! "!%" &!" '()(*()) ) +,!$$-$ ..V 2 ISBN C D E E F C F ! "# $ " % # "$ &'()" "*+,'-(. "/ GHJ K LK MM FM O P Till Sven och Freja List of Papers This thesis is based on the following published papers and manuscripts, which are referred to in the text by their Roman numerals. I Havelius, K. G. V., Su, J.-H., Feyziyev, Y., Mamedov, F. and Styring, S. (2006) The spectral resolution of the split EPR- signals induced by illumination at 5 K from the S1, S3 and S0 states of photosystem II, Biochemistry, 45:9279–9290. II Su, J.-H., Havelius, K. G. V., Feyziyev, Y., Mamedov, F., Ho, F. M. and Styring S. (2006) Split EPR signals from photosys- tem II are modified by methanol, reflecting S state dependent binding and alterations in the magnetic coupling in the CaMn4 cluster, Biochemistry, 45:7617–7627. III Havelius, K. G. V. and Styring, S. (2007) pH dependent compe- tition between YZ and YD in photosystem II probed by illumina- tion at 5 K, Biochemistry, 46:7865–7874. IV Su, J.-H., Havelius, K. G. V., Ho, F. M., Han, G., Mamedov, F. and Styring, S. (2007) Formation spectra of the EPR split signal from S0, S1 and S3 States in photosystem II induced by mono- chromatic light at 5 K, Biochemistry, 46:10703-10712. V Han, G., Ho, F. M., Havelius, K. G. V., Morvaridi, S. F., Ma- medov, F. and Styring, S. (2008) Direct quantification of the four individual S states in photosystem II using EPR spectros- copy, Biochim. Biophys. Acta, 1777:496-503. VI Havelius, K.
    [Show full text]
  • Identification, Isolation and Antioxidant Activity of Pheophytin from Green Tea (Camellia Sinensis (L.) Kuntze)
    Available online at www.sciencedirect.com ScienceDirect Procedia Chemistry 14 ( 2015 ) 232 – 238 2nd Humboldt Kolleg in conjunction with the International Conference on Natural Sciences, HK-ICONS 2014 Identification, Isolation and Antioxidant Activity of Pheophytin from Green Tea (Camellia sinensis (L.) Kuntze) Lia Kusmitaa, Ika Puspitaningruma, Leenawaty Limantarab* aSTIFAR “Yayasan Pharmasi”, Letjend Sarwo Edie Wibowo KM 1, Semarang 50193 bMa Chung Research Center for Photosyntehtic Pigments, Ma Chung University, Villa Puncak Tidar N 1,Malang 65151 Abstract Tea is a plant that can grow in different countries in the world. Green tea is one of the types of tea which is most beneficial for health such as anticarcinogenic, antibacterial, antitumor, antivirus, and antioxidant. In this research, identification of green tea pigments (Camellia sinensis (L.) Kuntze) were conducted by using thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) equipped with photodiode array detector. By TLC analysis, five spots were detected and they were β-carotene, pheophytin a, chlorophyll b, xanthophyll, and pheophorbide a. An analysis using HPLC showed the existence of 14 peaks consisting of 10 chlorophyll peaks and their derivatives as well as four carotenoid peaks. Pheophytin isolation was conducted using column chromatography and antioxidant activity was assayed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) –1 method. Antioxidant activity of pheophytin a IC50 = (573 ± 0.23) mg · L corresponded to that of β-carotene marker IC50 = –1 –1 (550 ± 0.26) mg · L . Antioxidant activity of the green tea crude extract had IC50 = (250 ± 0.21) mg · L which was twice higher than β-carotene marker. © 2015 Published by Elsevier B.V.
    [Show full text]
  • Continuous Chlorophyll Degradation Accompanied by Chlorophyllide and Phytol Reutilization for Chlorophyll Synthesis in Synechocystis Sp
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Biochimica et Biophysica Acta 1767 (2007) 920–929 www.elsevier.com/locate/bbabio Continuous chlorophyll degradation accompanied by chlorophyllide and phytol reutilization for chlorophyll synthesis in Synechocystis sp. PCC 6803 ⁎ Dmitrii Vavilin, Wim Vermaas School of Life Sciences and Center for the Study of Early Events in Photosynthesis, Arizona State University, Box 874501, Tempe, AZ 85287, USA Received 3 January 2007; received in revised form 23 March 2007; accepted 27 March 2007 Available online 3 April 2007 Abstract Chlorophyll synthesis and degradation were analyzed in the cyanobacterium Synechocystis sp. PCC 6803 by incubating cells in the presence of 13C-labeled glucose or 15N-containing salts. Upon mass spectral analysis of chlorophyll isolated from cells grown in the presence of 13C-glucose for different time periods, four chlorophyll pools were detected that differed markedly in the amount of 13C incorporated into the porphyrin (Por) and phytol (Phy) moieties of the molecule. These four pools represent (i) unlabeled chlorophyll (12Por12Phy), (ii) 13C-labeled chlorophyll (13Por13Phy), and (iii, iv) chlorophyll, in which either the porphyrin or the phytol moiety was 13C-labeled, whereas the other constituent of the molecule remained unlabeled (13Por12Phy and 12Por13Phy). The kinetics of 12Por12Phy disappearance, presumably due to chlorophyll de- esterification, and of 13Por12Phy, 12Por13Phy, and 13Por13Phy accumulation due to chlorophyll synthesis provided evidence for continuous chlorophyll turnover in Synechocystis cells. The loss of 12Por12Phy was three-fold faster in a photosystem I-less strain than in a photosystem II- less strain and was accelerated in wild-type cells upon exposure to strong light.
    [Show full text]
  • Bacteriopheophytin G
    Proc. Nati. Acad. Sci. USA Vol. 84, pp. 2570-2574, May 1987 Chemistry Bacteriopheophytin g: Properties and some speculations on a possible primary role for bacteriochlorophylls b and g in the biosynthesis of chlorophylls (photoisomerization/esterifying alcohol/electron spin resonance) T. J. MICHALSKI, J. E. HUNT, M. K. BOWMAN, U. SMITH, K. BARDEEN, H. GEST*, J. R. NORRIS, AND J. J. KATZ Chemistry Division, Argonne National Laboratory, Argonne, IL 60439 Contributed by J. J. Katz, January 14, 1987 ABSTRACT Bacteriopheophytin g and small amounts of characterized Bpheog by HPLC, and 252CF plasma desorp- bacteriochlorophyll g have been obtained in high purity from tion mass spectrometry (252Cf-PDMS). We have also studied the recently discovered photosynthetic bacterium Heliobacte- triplet Bpheog (3Bpheog) and the cation free radical BPheog' rium chlorum. Preparative methods and precautions in han- by ESR. Because of the high current interest in the structure dling these sensitive compounds are described. The compounds of bacterial photosynthetic reaction centers (6, 7), the reac- have been characterized by californium-252 plasma desorption tion center of H. chlorum has quickly attracted attention mass spectrometry, HPLC, visible absorption, and electron (8-10). The extreme sensitivity of BChlg to light and air was spin resonance spectroscopy. Our results agree with the struc- not adequately taken into consideration in the early reaction ture of bacteriochlorophyli g advanced by H. Brockmann and center work, and it will be necessary to do so in future A. Lipinski [(1983) Arch. Microbiol. 136, 17-191, with the reaction center research on this organism. exception that we find the esterifying alcohol to be farnesol and not geranylgeraniol as originally suggested.
    [Show full text]
  • University Microfilms, Inc., Ann Arbor. Michigan a COMPARATIVE STUDY of PHEOPHYTIN a and of PHEOPHYTIN B MONOLAYERS
    This dissertation has bean I microfilmed exactly as received ^7-16,272 DITMARS Jr., Walter Earl, 1923- A COMPARATIVE STUDY OF PHEOPHYTIN a AND OF PHEOPHYTIN b MONOLAYERS. The Ohio State University, Ph.D., 1967 Chemistry, plysical University Microfilms, Inc., Ann Arbor. Michigan A COMPARATIVE STUDY OF PHEOPHYTIN a AND OF PHEOPHYTIN b MONOLAYERS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University by Walter Earl Ditmars Jr., B*Sc., M,Sc, The Ohio State University 1967 Approved by r Adviser Department of Chemistry ACKNOWLEDGMENTS I wish to thank my adviser, Professor Quentin Van Vifinkle, for his continued interest and support in initiating and bringing to fruit the research reported herein. It is an understatement to say that without his unusual courage of moral conviction and high standards for academic performance this work could not have come into being. I wish to acknowledge the assistance of the members of the Chemistry Department Machine and Glassblowers Shops in construc­ tion of various pieces of apparatus used in the research. I am indebted to H.F. Blanck Jr., P. Kullavanijaya, and J, Larry for assistance in calculations of the osciallator and dipole strengths of the visible and ultraviolet light absorption of the chlorophylls and several of their derivatives, I wish to thank H.F. Blanck Jr., and J. Larry for as­ sistance in performing the work on the spectroscopic and stability studies, and for many stimulating discussions. I am especially appreciative for the support my family has given me, and for the patience shown in the hardships endured to accomplish this work.
    [Show full text]
  • Chlorophyll Catabolism in Senescing Plant Tissues
    Proc. Natl. Acad. Sci. USA Vol. 84, pp. 1901-1905, April 1987 Botany Chlorophyll catabolism in senescing plant tissues: In vivo breakdown intermediates suggest different degradative pathways for Citrus fruit and parsley leaves (chlorophyliide/pheophorbide/pheophytin/ethylene/chlorophyliase) DEKEL AMIR-SHAPIRA, ELIEZER E. GOLDSCHMIDT*, AND ARIE ALTMAN Department of Horticulture, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel Communicated by Kenneth V. Thimann, November 3, 1986 ABSTRACT High-pressure liquid chromatography was Reports on "changed chlorophylls" (11, 12) were not con- used to separate chlorophyll derivatives in acetone extracts firmed by more recent studies. from senescing Citrus fruit peel, autumnal Melia azedarach L. Renewed interest in the area of chlorophyll catabolism in leaves, and dark-held detached parsley (Petroselinum sativum recent years has produced developments along several lines L.) leaves. Chlorophyllide a and another polar, dephytylated of investigation. derivative accumulated in large amounts in senescing Citrus (i) The chlorophyllase enzyme has been thoroughly puri- peel, particularly in fruit treated with ethylene. Ethylene also fied and characterized (13, 14), and its localization in induced a 4-fold increase in the specific activity of Citrus chloroplasts seems well established (15, 16). Correlative chlorophyllase (chlorophyll chlorophyllidohydrolase, EC evidence in senescing leaves (17) and the upsurge of 3.1.1.14). Detailed kinetics based on a hexane/acetone solvent chlorophyllase in ethylene-treated Citrus fruit (16, 18-20) partition system showed that the in vivo increase in dephytyl- further support its role in senescent chlorophyll catabolism. ated derivatives coincided with the decrease in total chloro- (ii) Several oxidative and peroxidative enzyme systems phyll.
    [Show full text]