DOCSLIB.ORG

1 Dynamics and Mechanism of Short-Range Electron Transfer

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
1 Dynamics and Mechanism of Short-Range Electron Transfer Dynamics and Mechanism of Short-Range Electron Transfer Reactions in Flavoproteins Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Mainak Kundu, M.Sc. Graduate Program in Chemistry The Ohio State University 2019 Dissertation Committee Professor Dongping Zhong, Advisor Professor Heather Allen Professor Sherwin Singer 1 Copyrighted by Mainak Kundu 2019 2 Abstract Short-range electron transfer (ET) reactions are extensively used in light perception processes in flavoproteins. Such reactions an ultrafast and occur on the similar timescales as local protein-solvent fluctuations from femtoseconds to picoseconds and thus the two dynamics are expected to be coupled. Using the model protein of flavodoxin in its semiquinone state, we systematically characterized the photoinduced redox cycle of charge separation and charge recombination with mutations of different aromatic electron donors (tryptophan and tyrosine) and local residues to change the redox properties. We observed the ET dynamics in a few picoseconds, strongly following a stretched behavior resulting from a coupling between local environment fluctuations and these ET processes. We further observed the hot vibrational-state formation through charge recombination and the subsequent cooling dynamics and both processes are also in a few picoseconds. Combined with our previous studies of femtosecond ET in oxidized flavodoxin, these results coherently reveal the evolution of the ET dynamics from single to stretched exponential behaviors and elucidate the coupling mechanism. The observed hot vibration-state formation is robust and general and should be considered in all photoinduced back ET processes in flavoproteins. To analyze the role of tunneling distances in such reactions, we determined ET dynamics in a flavin–tryptophan pair at distances ranging from 3.2 to 18 Å, in 10 ii flavodoxin mutants with constant driving forces. We widely observed the stretched ET behavior with coupling from local solvation processes, and heterogenous ET dynamics from the large fluctuations (0.4 to 0.8 Å) in W donors located in flexible loop regions. We further observed the exponentially correlated distance–dependent ET severely impacted by local protein structures. At short distances, ET is highly favored by overlapping orbital interactions. At longer separation, tunneling pathways may uniquely differ within a protein and alter tunneling barriers to change the ET dynamics. Slow ET dynamics at long distances leads to energy loss via triplet dynamics, consistent with lower reaction yields. These results reveal how donor–acceptor configurations control ET mechanisms and signal transduction in photoreceptors. The accelerated growth in Oryza Sativa by the trimeric protein OsHAl3 is regulated by blue light through an unknown mechanism. We identified a photoreduction of the chromophore FMN from electron donors W79 and W82 on blue light illumination. At the active site, we obtained solvation dynamics in the ET-inert mutant in 1.9 ps (20%), 16 ps (42%), and 480 ps (37%), with the large energy relaxation of 217 cm-1, thus revealing a water-exposed FMN environment. We identified ultrafast forward ET and back ET dynamics in 1.2 ps, β=0.92 and 0.6 ps, β=0.97 for the donor W79. For W82, we resolved a faster forward ET and a slower back ET reaction in 4.0 ps, β=0.96 and 0.41 ps, β=1.0, respectively. With faster formation and longer recombination dynamics, W82 is the main electron donor, and the charge-separated intermediate could be key to downstream signaling. The large β values indicate minor ET coupling with solvent motions due to the slower environmental relaxations. We also observed formation of vibrationally hot BET iii product, consistent with the flavodoxin ET processes. These ET dynamics are essential for the blue light perception and is the primary event for signal transduction. For the special mutant C119S, we observed ET dynamics comparable to the wild-type, indicating absence of C119–C125 disulfide bond, in contrast to the light-inactive homolog AtHAL3. Together with the observation of C119-C125 disulfide bond in light structure of OsHAL3, the cysteines are possibly responsible for light induced structural changes. iv Dedication This document is dedicated to my friends and family. v Acknowledgments I take this opportunity to express my gratitude to my advisor Dr. Dongping Zhong for his dependable support and patience throughout my graduate studies. I thank him for his leadership and all the discussions on planning experiments, data analysis and manuscript preparation at various stages of research. His consistent guidance and scientific insight have been instrumental in the successful completion of this dissertation. I am grateful to Dr. Heather Allen and Dr. Sherwin Singer for their support and serving on my candidacy committee, annual progress reports, and the dissertation committee. I have also enjoyed learning the various physical chemistry courses they have taught. I thank Ms. Lijuan Wang for her help with biochemistry experiments, particularly during OsHAL3 purification. I specially thank Dr. Ting-Fang He for her preceding contributions in studying the protein flavodoxin, that paved the way for my research in electron transfer. I thank Drs. Zheyun Liu, Yangzhong Qin, Meng Zhang and Xiankun Li for their help with experiments and scientific discussions. I appreciate discussions with Dr. Xiaojing Yang from UIC, Chicago, and collaborations for the OsHAL3 project, and Dr. Richard Swenson for the gift of Flavodoxin plasmid. I also thank National Science Foundation for financial support and the Ohio Supercomputer Center for the computing facility. vi I like to thank Drs. Pratik Sen, Tarasankar Pal, Anjali Pal, Samrajnee Dutta, and my family for their support and encouragement that inspired me to pursue graduate studies. I am truly thankful to my friends, who have offered me help, advice and support on numerous occasions during my Ph.D. journey. vii Vita 2009 B.Sc. Chemistry. Presidency College, Calcutta University, India. Awarded Certificate of Merit, for top-10 university rank. 2011 M.Sc. Chemistry. Indian Institute of Technology Kanpur, India. Dissertation: Spectroscopic Investigation of Synergistic Chloroform- Methanol Binary Mixture. 2012–present Graduate Teaching and Research Associate, Department of Chemistry and Biochemistry, The Ohio State University. Publications 4. Short-range electron transfer in reduced flavodoxin: Ultrafast nonequilibrium dynamics coupled with protein fluctuations. M. Kundu, T-F. He, Y. Lu, L. Wang, and D. Zhong, J. Phys. Chem. Lett. (2018). 3. Galvanic replacement of As(0) nanoparticles by Au(III) for nanogold fabrication and SERS application. S. Saha, S. Maji, R. Sahoo, M. Kundu, A. Kundu, and A. Pal, New J. Chem. (2014). 2. Wet-chemical synthesis of spherical arsenic nanoparticles by a simple reduction method and its characterization. S. Saha, S. Maji, M. Kundu, A. Kundu, and A. Pal, Adv. Mat. Lett. (2012). viii 1. Origin of strong synergism in weakly perturbed binary solvent system: A case study of primary alcohols and chlorinated methanes. S. Gupta, S. Rafiq, M. Kundu, and P. Sen, J. Phys. Chem. B (2011). Fields of Study Major Field: Chemistry ix Table of Contents Abstract ............................................................................................................................... ii Dedication ........................................................................................................................... v Acknowledgments.............................................................................................................. vi Vita ................................................................................................................................... viii List of Tables .................................................................................................................... xii List of Figures .................................................................................................................. xiii Chapter 1. Introduction ....................................................................................................... 1 1.1 Photoreceptors and photoenzymes ............................................................................ 1 1.2 Flavoproteins............................................................................................................. 2 1.2.1 Flavodoxin and electron transfer processes ....................................................... 2 1.2.2 The Hal3 gene and bioregulation ....................................................................... 4 1.4 Methodology: Femtosecond-resolved spectroscopy ................................................. 5 Chapter 2. Short-Range Electron Transfer in Reduced Flavodoxin: Ultrafast Nonequilibrium Dynamics Coupled with Protein Fluctuations. ....................................... 12 2.1. Introduction ............................................................................................................ 12 2.2. Materials and methods ........................................................................................... 13 2.2.1. Protein purification ......................................................................................... 13 2.2.2. Femtosecond–resolved spectroscopy .............................................................. 13 2.3. Results and discussions .........................................................................................
Load more

Recommended publications
  • Sulphate-Reducing Bacteria's Response to Extreme Ph Environments and the Effect of Their Activities on Microbial Corrosion
    applied sciences Review Sulphate-Reducing Bacteria’s Response to Extreme pH Environments and the Effect of Their Activities on Microbial Corrosion Thi Thuy Tien Tran 1 , Krishnan Kannoorpatti 1,* , Anna Padovan 2 and Suresh Thennadil 1 1 Energy and Resources Institute, College of Engineering, Information Technology and Environment, Charles Darwin University, Darwin, NT 0909, Australia; [email protected] (T.T.T.T.); [email protected] (S.T.) 2 Research Institute for the Environment and Livelihoods, College of Engineering, Information Technology and Environment, Charles Darwin University, Darwin, NT 0909, Australia; [email protected] * Correspondence: [email protected] Abstract: Sulphate-reducing bacteria (SRB) are dominant species causing corrosion of various types of materials. However, they also play a beneficial role in bioremediation due to their tolerance of extreme pH conditions. The application of sulphate-reducing bacteria (SRB) in bioremediation and control methods for microbiologically influenced corrosion (MIC) in extreme pH environments requires an understanding of the microbial activities in these conditions. Recent studies have found that in order to survive and grow in high alkaline/acidic condition, SRB have developed several strategies to combat the environmental challenges. The strategies mainly include maintaining pH homeostasis in the cytoplasm and adjusting metabolic activities leading to changes in environmental pH. The change in pH of the environment and microbial activities in such conditions can have a Citation: Tran, T.T.T.; Kannoorpatti, significant impact on the microbial corrosion of materials. These bacteria strategies to combat extreme K.; Padovan, A.; Thennadil, S. pH environments and their effect on microbial corrosion are presented and discussed.
    [Show full text]
  • Synthesis and Photoinduced Electron Transfer of Donor-Sensitizer-Acceptor Systems
    Synthesis and Photoinduced Electron Transfer of Donor-Sensitizer-Acceptor Systems Yunhua Xu Stockholm University 2005 1 Synthesis and Photoinduced Electron Transfer of Donor-Sensitizer-Acceptor Systems Akademisk avhandling som för avläggande av filosofie doktorsexamen vid Stockholms Universitet, tillsammans med arbetena I-VII, offentligen kommer att försvaras i Magnélisalen, Kemiska övnings-laboratoriet, Svante Arrhenius väg 16, onsdagen den 20 april 2005, klockan 10.00. Av Yunhua Xu Avhandlingen försvaras på engelska Institutionen för organisk kemi ISBN 91-7155-034-8 pp 1-53 Arrheniuslaboratoriet Stockholm 2005 Stockholms Universitet 106 91 Stockholm Abstract Artificial systems involving water oxidation and solar cells are promising ways for the conversion of solar energy into fuels and electricity. These systems usually consist of a photosensitizer, an electron donor and / or an electron acceptor. This thesis deals with the synthesis and photoinduced electron transfer of several donor-sensitizer- acceptor supramolecular systems. The first part of this thesis describes the synthesis and properties of two novel dinuclear ruthenium complexes as electron donors to mimic the donor side reaction of Photosystem II. These two Ru2 complexes were then covalently linked to ruthenium trisbipyridine and the properties of the resulting trinuclear complexes were studied by cyclic voltammetry and transient absorption spectroscopy. The second part presents the synthesis and photoinduced electron transfer of covalently linked donor-sensitizer supramolecular systems in the presence of TiO2 as electron acceptors. Electron donors are tyrosine, phenol and their derivatives, and dinuclear ruthenium complexes. Intramolecular electron transfer from the donor to the oxidized sensitizer was observed by transient absorption spectroscopy after light 2+ excitation of the Ru(bpy)3 moiety.
    [Show full text]
  • Donor/Acceptor Electronic Coupling Is a Dynamical Variable Edward W
    Claremont Colleges Scholarship @ Claremont All HMC Faculty Publications and Research HMC Faculty Scholarship 1-1-2000 Solvent as Electron Donor: Donor/Acceptor Electronic Coupling Is a Dynamical Variable Edward W. Castner Jr. Rutgers University Darcy Kennedy '00 Claremont McKenna College Robert J. Cave Harvey Mudd College Recommended Citation Castner, E.W. Jr.; Kennedy, D.; Cave, R.J. “Solvent as Electron Donor: Donor/Acceptor Coupling is a Dynamical Variable,” J. Phys. Chem. A 2000, 104, 2869. DOI: 10.1021/jp9936852 This Article is brought to you for free and open access by the HMC Faculty Scholarship at Scholarship @ Claremont. It has been accepted for inclusion in All HMC Faculty Publications and Research by an authorized administrator of Scholarship @ Claremont. For more information, please contact [email protected]. J. Phys. Chem. A 2000, 104, 2869-2885 2869 ARTICLES Solvent as Electron Donor: Donor/Acceptor Electronic Coupling Is a Dynamical Variable Edward W. Castner, Jr.*,† BrookhaVen National Laboratory, Chemistry Department, Building 555A, Upton, New York 11973-5000 Darcy Kennedy and Robert J. Cave*,‡ HarVey Mudd College, Department of Chemistry, Claremont, California 91711 ReceiVed: October 14, 1999; In Final Form: December 24, 1999 We combine analysis of measurements by femtosecond optical spectroscopy, computer simulations, and the generalized Mulliken-Hush (GMH) theory in the study of electron-transfer reactions and electron donor- acceptor interactions. Our focus is on ultrafast photoinduced electron-transfer reactions from aromatic amine solvent donors to excited-state acceptors. The experimental results from femtosecond dynamical measurements fall into three categories: six coumarin acceptors reductively quenched by N,N-dimethylaniline (DMA), eight electron-donating amine solvents reductively quenching coumarin 152 (7-(dimethylamino)-4-(trifluoromethyl)- coumarin), and reductive quenching dynamics of two coumarins by DMA as a function of dilution in the nonreactive solvents toluene and chlorobenzene.
    [Show full text]
  • Ocean Life, Bioenergetics and Metabolism
    Ocean life, bioenergetics and metabolism Biological Oceanography (OCN 621) Matthew Church (MSB 612) Ecosystems are hierarchically organized • Atoms → Molecules → Cells → Organisms→ Populations→ Communities • This organizational system dictates the pathways that energy and material travel through a system. • Cells are the lowest level of structure capable of performing ALL the functions of life. Classification of life Two primary cellular forms • Prokaryotes: lack internal membrane-bound organelles. Genetic information is not separated from other cell functions. Bacteria and Archaea are prokaryotes. Note however this does not imply these divisions of life are closely related. • Eukaryotes: membrane-bound organelles (nucleus, mitochrondrion, etc .). Compartmentalization (organization) of different cellular functions allows sequential intracellular activities In the ocean, microscopic organisms account for >50% of the living biomass. Controls on types of organisms, abundances, distributions • Habitat: The physical/chemical setting or characteristics of a particular environment, e.g., light vs. dark, cold vs. warm, high vs. low pressure • Each marine habitat supports a somewhat predictable assemblage of organisms that collectively make up the community, e.g., rocky intertidal community, coral reef community, abyssobenthic community • The structure and function of the individuals/populations in these communities arise from evolution and selective adaptations in response to the habitat characteristics • Niche: The role of a particular organism in an integrated community •The ocean is not homogenous: spatial and temporal variability in habitats Clearly distinguishable ocean habitats with elevated “plant” biomass in regions where nutrients are elevated The ocean is stirred more than mixed Sea Surface Temperature Chl a (°C) (mg m-3) Spatial discontinuities at various scales (basin, mesoscale, microscale) in ocean habitats play important roles in controlling plankton growth and distributions.
    [Show full text]
  • Introduction to Biological Chemistry
    CHAPTER Introduction to Biological Chemistry Reza Karimi 1 1. Learn about the basic chemistry related to atoms and molecules. Understand the roles of orbitals and lone-pair electrons in a few common atoms (e.g., N, F, C, O) and comprehend nucleophilic/electrophilic attacks and their impact on oxidation, reduction, addition, and substitution reactions. 2. List and explain the importance of medicinal functional groups that commonly are found in drug molecules and appreciate the important roles that drug structures play in pharmaceutical sciences. 3. Understand basic concepts in acid–base theory and their roles in the structures of drug molecules. 4. Learn about salt formation, ionization, and water solubility of drug molecules, and explain the role of medici- nal functional groups in ionization, salt formation, salt hydrolysis, and water solubility of drug molecules. CHAPTER OUTLINE CHAPTER 5. Implement a series of Learning Bridge assignments at your experiential sites to bridge your didactic learning with your experiential experiences. S 1. Brønsted-Lowry acid–base: definition used to express the acidic or basic properties of acids and bases. E V 2. Buffer: a mixture of an acid and its conjugate base in a solution that causes the solution to resist a pH change. 3. Compound: a combination of two or more substances, ingredients, or elements. While the ecti J majority of drugs on the market are compounds, not all compounds are drugs. B 4. Conjugate acid: a base that has gained a proton. O 5. Conjugate base: an acid that has lost its proton. 6. Covalence: the number of covalent bonds present.
    [Show full text]
  • Influence of Electron Acceptor and Electron Donor on The
    FULL PAPER Carbon Dots www.afm-journal.de Influence of Electron Acceptor and Electron Donor on the Photophysical Properties of Carbon Dots: A Comparative Investigation at the Bulk-State and Single-Particle Level Indrajit Srivastava, John S. Khamo, Subhendu Pandit, Parinaz Fathi, Xuedong Huang, Anleen Cao, Richard T. Haasch, Shuming Nie, Kai Zhang,* and Dipanjan Pan* photocatalysis, photovoltaic applications, Carbon dots (CDs) are extensively studied to investigate their unique optical and bioimaging.[1–15] These nanodots have properties such as undergoing electron transfer in different scenarios. This a multitude of intriguing advantages, work presents an in-depth investigation to study the ensemble-averaged such as their water solubility, low toxicity, state/bulk state and single-particle level photophysical properties of CDs high biocompatibility, easy synthesis tech- niques, and complementary energy and that are passivated with electron-accepting (CD-A) and electron-donating charge transfer properties.[16–25] However, molecules (CD-D) on their surface. The bulk-state experiments reveal that in a despite considerable efforts, many ques- mixture of these CDs, CD-A dominates the overall photophyiscal properties and tions remain about the intrinsic mecha- eventually leads to formation of at least two associated geometries, which is nisms governing their photoluminescence dependent on time, concentration, intramolecular electron/charge transfer, and (PL) and its subsequent capability to par- ticipate in photoinduced charge-transfer hydrogen bonding. Single-particle studies, however, do not reveal an “acceptor- processes.[26,27] dominating” scenario based on analysis of instantaneous intensity, bleaching For charge-transfer processes, having kinetics, and photoblinking, indicating that the direct interaction of these CDs a precise control over the interactions may affect their photophysical properties in the bulk state due to formation of between the two components is of hierarchical structural assemblies.
    [Show full text]
  • Electron Donor and Acceptor Utilization by Halorespiring Bacteria'
    Electron donor andaccepto r utilizationb y halorespiring bacteria Maurice L.G.C. Luijten CENTRALS LANDBOUWCATALOGUS 0000 0950 9080 Promotoren Prof.dr .W.M . de Vos Hoogleraar ind eMicrobiologi c Wageningen Universiteit Prof.dr .ir .A.J.M .Stam s Persoonlijk hoogleraar bij hetlaboratoriu mvoo r Microbiologic Laboratorium voor Microbiologic, Wageningen Universiteit Copromotoren Dr.G .Schra a Universitair docent Laboratorium voor Microbiologic, Wageningen Universiteit Dr.A.A.M . Langenhoff Senior researcher/project leader Milieubiotechnologie, TNO-MEP Promotiecommissie Prof. E.J.Bouwe r John's Hopkins University, Baltimore, USA Prof.dr .C .Hollige r EPFL, Lausanne, Switzerland Dr.F .Volkerin g Tauw bv, Deventer, Nederland Prof. dr.ir .W.H . Rulkens Wageningen Universteit Dit onderzoek is uitgevoerd binnen de onderzoekschool SENSE (Netherlands Research School forth e Socio-Economic andNatura l Sciences ofth e Environment). LV''-:- v. •:-:::'.Ifir Electron donor and acceptor utilizationb y halorespiring bacteria Maurice L.G.C.Luijte n Proefschrift Terverkrijgin g van de graadva n doctor opgeza gva n derecto r magnificus van Wageningen Universiteit, prof. dr. ir. L. Speelman, inhe t openbaar te verdedigen opvrijda g 11 juni 2004 desnamiddag s te half twee in deAula . \ '\ i ocXi ^ Electron donor and acceptor utilization byhalorespirin g bacteria Maurice L.G.C. Luijten Ph.D.thesi sWageninge n University, Wageningen, The Netherlands 2004 ISBN 90-5804-067-1 Front cover: Modified EMpictur e ofSulfurospirillum halorespirans PCE-M2 — ry ' Stellingen 1.El k nadeel heb zijn voordeel. Dit proefschrift. 2. De ene volledige reductie van PCE is de andere nog niet. Dit proefschrift. 3. Sectorale communicatie reikt niet ver genoeg. HRH the Prince of Orange, Wat.
    [Show full text]
  • A Structural Basis of Light Energy and Electron Transfer in Biology*
    The EMBO Journal vol.8 no.8 pp.2125-2147, 1989 NOBEL LECTURE A structural basis of light energy and electron transfer in biology* Robert Huber bacterial phycobilisomes and blue oxidases. A wealth of structural and functional data is available for these three Max-Planck-Institut fiir Biochemie, D-8033 Martinsried, FRG systems, which make them uniquely appropriate examples *Dedicated to Christa. from which to derive general principles of light energy and electron transfer in biological materials. Indeed, there are Aspects of intramolecular light energy and electron few systems known in sufficient detail for such purposes. transfer will be discussed for three protein-cofactor [The strucure of the Rhodobacter sphaeroides reaction centre complexes, whose three-dimensional structures have been (RC) is closely related to the R. viridis RC (Allen et al., elucidated by X-ray crystallography: components of light- 1986, 1987; Chang et al., 1986). A green bacterial harvesting cyanobacterial phycobilisomes; the purple bacteriochlorophyll-a-containing light-harvesting protein is bacterial reaction centre; and the blue multi-copper well defined in structure (Tronrud et al., 1986) but not in oxidases. A wealth of functional data is available for these function. In the multihaem cytochromes (Pierrot et al., 1982; systems which allows specific correlations between Higuchi et al., 1984) the existence/or significance of intra- structure and function and general conclusions about molecular electron transfer is unclear.] light energy and electron transfer in biological materials We strive to understand the underlying physical principles to be made. of light and electron conduction in biological materials with considerable hope for success as these processes appear to be more tractable than other biological reactions, which involve diffusive motions of substrates and products and Introduction intramolecular motions.
    [Show full text]
  • Electron Donor Limitation of the Biosphere Before the Origin of Oxygenic Photosynthesis
    9 Chapter 1 ELECTRON DONOR LIMITATION OF THE BIOSPHERE BEFORE THE ORIGIN OF OXYGENIC PHOTOSYNTHESIS Ward, Lewis M., Birger Rasmussen, and Woodward W. Fischer. In preparation. Abstract: The evolution of oxygenic photosynthesis, and the resulting oxygenation of the atmosphere ~2.3 billion years ago, was the single largest shift in the size and structure of the biosphere since the origin of life. Oxygen-fueled metabolisms are highly energetic, and drove the evolution of complex life in Neoproterozoic and Phanerozoic time, and oxygenic photosynthesis itself came to dominate primary productivity on the surface of the Earth. Perhaps more revolutionary than the introduction of molecular oxygen, oxygenic photosynthesis introduced the ability for life to utilize water—an essentially infinite electron donor—for autotrophy. Before the evolution of oxygenic photosynthesis, the biosphere was supported by anaerobic metabolisms such as methanogenesis, acetogenesis, and anoxygenic photosynthesis. In addition to being less energetic than oxygen-based metabolisms, these early autotrophic processes depend on geologically supplied electron donors such as molecular hydrogen and ferrous iron as a source of electrons for reducing CO2 to organic carbon. As a result, the geological fluxes of electron donors may have served as a fundamental limitation to the productivity of the early biosphere, rather than nutrients like phosphate or fixed nitrogen as today. Here, we integrate estimates for the geological fluxes of electron donor compounds, phosphate, and fixed nitrogen to determine the fundamental limits to pre-oxygen productivity. We demonstrate that even if iron 10 oxidation was occurring, it was a relatively minor fuel for productivity compared to molecular hydrogen. Furthermore, we show that fluxes of fixed nitrogen and phosphate were substantially in excess of rates of productivity allowed by the supply of electron donor compounds, even in the absence of biological nitrogen fixation.
    [Show full text]
  • Quantum Yields for Oxygenic and Anoxygenic Photosynthesis in The
    Proc. Natl. Acad. Sci. USA Vol. 74, No. 5, pp. 2152-2156, May 1977 Microbiology Quantum yields for oxygenic and anoxygenic photosynthesis in the cyanobacterium Oscillatoria limnetica (blue-green algae/photosystem I growth/phototrophic evolution/H2S photooxidation) A. OREN*, E. PADAN*, AND M. AVRONt *Department of Microbiological Chemistry, The Hebrew University-Hadassah Medical School, Jerusalem, Israel; and tWeizmann Institute of Science, Rehovot, Israel Communicated by C. Stacy French, February 11, 1977 ABSTRACT A comparison of the quantum yield spectra the missing link between bacterial type and plant type photo- of the oxygenic (H20 as the electron donor) with the anoxygenic trophic metabolic patterns. (H2S as the electron donor) photosynthesis of the cyanobacte- In the with 0. rium, Oscillatoria limnetica reveals that anoxygenic photo- present work limnetica, the quantum yield synthesis is driven by photosystem I only. The highest quantum spectra of the oxygenic and anoxygenic photoassimilation of yields of the latter (maximum; 0.059 CO2 molecules/quantum CO2 were analyzed in order to unravel the pattern by which of absorbed light) were obtained with wavelengths which the absorbed spectrum is used in the two types of photosynthesis preferentially excite photosystem I (<550, >650) in which and to deduce the interrelationship between photosystem I and chlorophyll a and-carotenoids are the major pigments. The II in such an organism. addition of 3(3,4-dichlorophenyl)1,1-dimethylurea had no effect on anoxygenic photosynthesis, and no enhancement in quantum efficiency was observed by a superimposition of light prefer- MATERIALS AND METHODS entially exciting photosystem II. Cyanobacterial Strain and Culture Conditions. The 0.
    [Show full text]
  • Photosynthesis
    Photosynthesis Photosynthesis is the process by which plants, some bacteria and some protistans use the energy from sunlight to produce glucose from carbon dioxide and water. This glucose can be converted into pyruvate which releases adenosine triphosphate (ATP) by cellular respiration. Oxygen is also formed. Photosynthesis may be summarised by the word equation: carbon dioxide + water glucose + oxygen The conversion of usable sunlight energy into chemical energy is associated with the action of the green pigment chlorophyll. Chlorophyll is a complex molecule. Several modifications of chlorophyll occur among plants and other photosynthetic organisms. All photosynthetic organisms have chlorophyll a. Accessory pigments absorb energy that chlorophyll a does not absorb. Accessory pigments include chlorophyll b (also c, d, and e in algae and protistans), xanthophylls, and carotenoids (such as beta-carotene). Chlorophyll a absorbs its energy from the violet-blue and reddish orange-red wavelengths, and little from the intermediate (green-yellow-orange) wavelengths. Chlorophyll All chlorophylls have: • a lipid-soluble hydrocarbon tail (C20H39 -) • a flat hydrophilic head with a magnesium ion at its centre; different chlorophylls have different side-groups on the head The tail and head are linked by an ester bond. Leaves and leaf structure Plants are the only photosynthetic organisms to have leaves (and not all plants have leaves). A leaf may be viewed as a solar collector crammed full of photosynthetic cells. The raw materials of photosynthesis, water and carbon dioxide, enter the cells of the leaf, and the products of photosynthesis, sugar and oxygen, leave the leaf. Water enters the root and is transported up to the leaves through specialized plant cells known as xylem vessels.
    [Show full text]
  • GLOSSARY of TERMS USED in BIOINORGANIC CHEMISTRY* GLOSSARY of TERMS USED in BIOINORGANIC CHEMISTRY (IUPAC Recommendations 1997)
    Pure &App/. Chem., Vol. 69, No. 6, pp. 1251-1303, 1997. Printed in Great Britain. Q 1997 IUPAC INTERNATIONAL UNION OF PURE AND APPLIED CHEMISTRY INORGANIC CHEMISTRY DIVISION WORKING PARTY ON IUPAC GLOSSARY OF TERMS USED IN BIOINORGANIC CHEMISTRY* GLOSSARY OF TERMS USED IN BIOINORGANIC CHEMISTRY (IUPAC Recommendations 1997) Prepared for publication by M. W. G. DE BOLSTER Vakgroep Organische en Anorganische Chemie, Faculteit der Scheikunde, Vrije Universiteit, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands *Membership of the Working Party during the preparation of this report (1992-96) was as follows: Chairman: M. W. G. de Bolster (Netherlands); Members: R. Cammack (UK); D. N. Coucouvanis (USA); J. Reedijk (Netherlands); C. Veeger (Netherlands). Republication or reproduction of this report or its storage and/or dissemination by electronic means is permitted without the need for formal IUPAC permission on condition that an acknowledgement, with full reference to the source along with use of the copyright symbol 0,the name IUPAC and the year of publication are prominently visible. Publication of a translation into another language is subject to the additional condition of prior approval from the relevant IUPAC National Adhering Organization. Glossary of terms used in bioinorganic chemistry (IUPAC Recommendations 1997) Abstract: The glossary contains definitions and (where needed) explanatory notes for about 400 terms used in the multidisciplinary field of bioinorganic chemistry. A need has been recognized for globally acceptable definitions of terms in this field and this glossary was compiled with the objective of fulfilling this need. It is by no means a comprehensive dictionary. The terms selected were those considered essential and/or widely used.
    [Show full text]