Chlorophyllides: Preparation, Purification, and Application
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Spectroscopy of Porphyrins
BORIS F. KIM and JOSEPH BOHANDY SPECTROSCOPY OF PORPHYRINS Porphyrins are an important class of compounds that are of interest in molecular biology because of the important roles they play in vital biochemical systems such as biochemical energy conversion in animals, oxygen transport in blood, and photosynthetic energy conversion in plants. We are studying the physical properties of the energy states of porphyrins using the techniques of ex perimental and theoretical spectroscopy with the aim of contributing to a basic understanding of their biochemical behavior. INTRODUCTION Metalloporphin Porphyrins are a class of complex organic chemical compounds found in such diverse places as crude oil, plants, and human beings. They are, in most cases, tailored to carry out vital chemical transformations in intricate biochemical or biophysical systems. They are the key constituents of chlorophyll in plants and of hemoglobin in animals. Without them, life would y be impossible. t Free base porphin These molecules display a wide range of chemical and physical properties that depend on the structural details of the particular porphyrin molecule. All por ~x phyrins are vividly colored and absorb light in the visible and ultraviolet regions of the spectrum. Some exhibit luminescence, paramagnetism, photoconduc tion, or semiconduction. Spme are photosensitizers Wavelength (nanometers) or catalysts. Scientists from several disciplines have been interested in unraveling the principles that cause Fig. 1-The chemical structures for the two forms of por· this diversity of properties. phin are shown on the left. A carbon atom and a hydrogen The simplest compound of all porphyrins is por atom are understood to be at each apex not attached to a nitrogen atom. -
1 Introduction
Introduction 1 1 Introduction Tetrapyrroles belong to a group of molecules with a common structure. They are synthesized in a branched pathway, in which various end products are formed to different amounts. The most abundant cyclic tetrapyrroles are chlorophyll (Chl) and heme, which are characterized by a chelated magnesium and ferrous ion, respectively. Chlorophyll is involved in light absorption and energy transduction during photosynthesis. Heme is a cofactor of hemoglobin, cytochromes, P450 mixed-function oxygenases, and catalases. Other members of the class of tetrapyrroles include siroheme (the prosthetic group of nitrite and sulphite reductases) and phytochromobilin, the chromophore of phytochrome, which is involved in light perception. Tetrapyrrole biosynthesis has been the subject of numerous studies over several decades. But genetic and biochemical characterization of tetrapyrrole biosynthesis has progressed by using approaches to genetically dissect the tetrapyrrole biosynthetic pathway. Pigment-deficient mutants and antisense technology have proved to be useful for examining the mechanisms of metabolic control or for analyzing biochemically the enzymatic steps which are affected by the mutation or by the antisense RNA expression. Tetrapyrrole intermediates are highly photoreactive. They can easily be excited and transfer the energy or electrons to O2. Then reactive oxygen species (ROS) are produced upon exposure to light and oxygen. Under normal growth conditions the risk of photooxidative damage from intermediates in tetrapyrrole biosynthesis is low. Excessive accumulation of such intermediates is the result of deregulation of tetrapyrrole biosynthesis. Toxic effects of porphyrins are evident in human patients with deficiencies of one of the enzymes of heme biosynthesis. These patients are suffering from metabolic diseases, which are called porphyrias (Moore, 1993). -
Light-Induced Psba Translation in Plants Is Triggered by Photosystem II Damage Via an Assembly-Linked Autoregulatory Circuit
Light-induced psbA translation in plants is triggered by photosystem II damage via an assembly-linked autoregulatory circuit Prakitchai Chotewutmontria and Alice Barkana,1 aInstitute of Molecular Biology, University of Oregon, Eugene, OR 97403 Edited by Krishna K. Niyogi, University of California, Berkeley, CA, and approved July 22, 2020 (received for review April 26, 2020) The D1 reaction center protein of photosystem II (PSII) is subject to mRNA to provide D1 for PSII repair remain obscure (13, 14). light-induced damage. Degradation of damaged D1 and its re- The consensus view in recent years has been that psbA transla- placement by nascent D1 are at the heart of a PSII repair cycle, tion for PSII repair is regulated at the elongation step (7, 15–17), without which photosynthesis is inhibited. In mature plant chloro- a view that arises primarily from experiments with the green alga plasts, light stimulates the recruitment of ribosomes specifically to Chlamydomonas reinhardtii (Chlamydomonas) (18). However, we psbA mRNA to provide nascent D1 for PSII repair and also triggers showed recently that regulated translation initiation makes a a global increase in translation elongation rate. The light-induced large contribution in plants (19). These experiments used ribo- signals that initiate these responses are unclear. We present action some profiling (ribo-seq) to monitor ribosome occupancy on spectrum and genetic data indicating that the light-induced re- cruitment of ribosomes to psbA mRNA is triggered by D1 photo- chloroplast open reading frames (ORFs) in maize and Arabi- damage, whereas the global stimulation of translation elongation dopsis upon shifting seedlings harboring mature chloroplasts is triggered by photosynthetic electron transport. -
Evolution of Photochemical Reaction Centres
bioRxiv preprint doi: https://doi.org/10.1101/502450; this version posted December 20, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 1 Evolution of photochemical reaction 2 centres: more twists? 3 4 Tanai Cardona, A. William Rutherford 5 Department of Life Sciences, Imperial College London, London, UK 6 Correspondence to: [email protected] 7 8 Abstract 9 The earliest event recorded in the molecular evolution of photosynthesis is the structural and 10 functional specialisation of Type I (ferredoxin-reducing) and Type II (quinone-reducing) reaction 11 centres. Here we point out that the homodimeric Type I reaction centre of Heliobacteria has a Ca2+- 12 binding site with a number of striking parallels to the Mn4CaO5 cluster of cyanobacterial 13 Photosystem II. This structural parallels indicate that water oxidation chemistry originated at the 14 divergence of Type I and Type II reaction centres. We suggests that this divergence was triggered by 15 a structural rearrangement of a core transmembrane helix resulting in a shift of the redox potential 16 of the electron donor side and electron acceptor side at the same time and in the same redox direction. 17 18 Keywords 19 Photosynthesis, Photosystem, Water oxidation, Oxygenic, Anoxygenic, Reaction centre 20 21 Evolution of Photosystem II 22 There is no consensus on when and how oxygenic photosynthesis originated. Both the timing and the 23 evolutionary mechanism are disputed. -
TION of BUCKWHEAT. It Has Been Known for a Long Time That Certain
PHOTOSENSITIZATION OF ANIMALS AFTER THE INGES- TION OF BUCKWHEAT. BY CHARLES SHEARD, PH.D., HAROLD D. CAYLOR, M.D., AND CARL SCHLOTTHAUER, D.V.M. (From tke Section on Pkysics and Biophysical Research, tke Section on Surgical Pathology, and the Division of Experimental Palhdogy and Surgery, Mayo Clinic and The Mayo Foundation, Rochester, Minnesota.) (Received for publication,~'March 1, 1928.) It has been known for a long time that certain animals, following the ingestion of various substances, are rendered sensitive to certain types of radiant energy. The present study covers biologic and physical observations on the degree of sensitization, the character of the sensitizing light and the nature of the photodynamic substance of buckwheat. White rabbits, mice, rats, goats, swine, dogs and varicolored guinea pigs were studied. Sunlight, carbon arc lamp (Efka or Hoffman) with Conradty-Norris vacuum carbon electrodes and quartz mercury vapor arcs (Victor X-Ray Corporation), both with and without various filters, were employed for irradiation. All of these sources contain infra-red, visible and ultra-violet radiations. I~SLr~ OF LITERATURE. Considerable literature, especially European, has appeared on the subject of diseases in animals and man brought about by optical sensitization. Somewhat detailed accounts of the contributions relative to diseases due to exogenous sensi- tization are to be found in the brochures by Hausmann and by Mayer. Years ago European stockmen found that in certain animals which had ingested buckwheat (plant or seed), erythema, itching, edema and convulsions developed and, in many cases, paralysis and death, on exposure to out-of-door sunshine. However, untoward symptoms did not arise if the animals were kept indoors or in partial darkness and they recovered from the sensitization induced by eating certain plants if they were removed from the light early in the onset of the symp- toms. -
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. -
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. -
Electronic Spectroscopy of Free Base Porphyrins and Metalloporphyrins
Absorption and Fluorescence Spectroscopy of Tetraphenylporphyrin§ and Metallo-Tetraphenylporphyrin Introduction The word porphyrin is derived from the Greek porphura meaning purple, and all porphyrins are intensely coloured1. Porphyrins comprise an important class of molecules that serve nature in a variety of ways. The Metalloporphyrin ring is found in a variety of important biological system where it is the active component of the system or in some ways intimately connected with the activity of the system. Many of these porphyrins synthesized are the basic structure of biological porphyrins which are the active sites of numerous proteins, whose functions range from oxygen transfer and storage (hemoglobin and myoglobin) to electron transfer (cytochrome c, cytochrome oxidase) to energy conversion (chlorophyll). They also have been proven to be efficient sensitizers and catalyst in a number of chemical and photochemical processes especially photodynamic therapy (PDT). The diversity of their functions is due in part to the variety of metals that bind in the “pocket” of the porphyrin ring system (Fig. 1). Figure 1. Metallated Tetraphenylporphyrin Upon metalation the porphyrin ring system deprotonates, forming a dianionic ligand (Fig. 2). The metal ions behave as Lewis acids, accepting lone pairs of electrons ________________________________ § We all need to thank Jay Stephens for synthesizing the H2TPP 2 from the dianionic porphyrin ligand. Unlike most transition metal complexes, their color is due to absorption(s) within the porphyrin ligand involving the excitation of electrons from π to π* porphyrin ring orbitals. Figure 2. Synthesis of Zn(TPP) The electronic absorption spectrum of a typical porphyrin consists of a strong transition to the second excited state (S0 S2) at about 400 nm (the Soret or B band) and a weak transition to the first excited state (S0 S1) at about 550 nm (the Q band). -
Comparing the Reaction Mechanism of Dark-Operative Protochlorophyllide
With or without light: comparing the reaction mechanism of dark-operative protochlorophyllide oxidoreductase with the energetic requirements of the light-dependent protochlorophyllide oxidoreductase Pedro J. Silva REQUIMTE, Faculdade de Cienciasˆ da Saude,´ Universidade Fernando Pessoa, Rua Carlos da Maia, Porto, Portugal ABSTRACT The addition of two electrons and two protons to the C17DC18 bond in protochloro- phyllide is catalyzed by a light-dependent enzyme relying on NADPH as electron donor, and by a light-independent enzyme bearing a .Cys/3Asp-ligated [4Fe–4S] cluster which is reduced by cytoplasmic electron donors in an ATP-dependent manner and then functions as electron donor to protochlorophyllide. The precise sequence of events occurring at the C17DC18 bond has not, however, been determined experimentally in the dark-operating enzyme. In this paper, we present the computational investigation of the reaction mechanism of this enzyme at the B3LYP/6-311CG(d,p)//B3LYP/6-31G(d) level of theory. The reaction mechanism begins with single-electron reduction of the substrate by the .Cys/3Asp-ligated [4Fe–4S], yielding a negatively-charged intermediate. Depending on the rate of Fe–S cluster re-reduction, the reaction either proceeds through double protonation of the single-electron-reduced substrate, or by alternating proton/electron transfer. The computed reaction barriers suggest that Fe–S cluster re-reduction should be Submitted 24 March 2014 the rate-limiting stage of the process. Poisson–Boltzmann computations on the Accepted 9 August 2014 full enzyme–substrate complex, followed by Monte Carlo simulations of redox Published 2 September 2014 and protonation titrations revealed a hitherto unsuspected pH-dependence of the Corresponding author reaction potential of the Fe–S cluster. -
Light-Independent Nitrogen Assimilation in Plant Leaves: Nitrate Incorporation Into Glutamine, Glutamate, Aspartate, and Asparagine Traced by 15N
plants Review Light-Independent Nitrogen Assimilation in Plant Leaves: Nitrate Incorporation into Glutamine, Glutamate, Aspartate, and Asparagine Traced by 15N Tadakatsu Yoneyama 1,* and Akira Suzuki 2,* 1 Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan 2 Institut Jean-Pierre Bourgin, Institut national de recherche pour l’agriculture, l’alimentation et l’environnement (INRAE), UMR1318, RD10, F-78026 Versailles, France * Correspondence: [email protected] (T.Y.); [email protected] (A.S.) Received: 3 September 2020; Accepted: 29 September 2020; Published: 2 October 2020 Abstract: Although the nitrate assimilation into amino acids in photosynthetic leaf tissues is active under the light, the studies during 1950s and 1970s in the dark nitrate assimilation provided fragmental and variable activities, and the mechanism of reductant supply to nitrate assimilation in darkness remained unclear. 15N tracing experiments unraveled the assimilatory mechanism of nitrogen from nitrate into amino acids in the light and in darkness by the reactions of nitrate and nitrite reductases, glutamine synthetase, glutamate synthase, aspartate aminotransferase, and asparagine synthetase. Nitrogen assimilation in illuminated leaves and non-photosynthetic roots occurs either in the redundant way or in the specific manner regarding the isoforms of nitrogen assimilatory enzymes in their cellular compartments. The electron supplying systems necessary to the enzymatic reactions share in part a similar electron donor system at the expense of carbohydrates in both leaves and roots, but also distinct reducing systems regarding the reactions of Fd-nitrite reductase and Fd-glutamate synthase in the photosynthetic and non-photosynthetic organs. -
1.1-Billion-Year-Old Porphyrins Establish a Marine Ecosystem Dominated by Bacterial Primary Producers
1.1-billion-year-old porphyrins establish a marine ecosystem dominated by bacterial primary producers N. Guenelia,1, A. M. McKennab, N. Ohkouchic, C. J. Borehamd, J. Beghine, E. J. Javauxe, and J. J. Brocksa,1 aResearch School of Earth Sciences, Australian National University, Canberra, ACT 2601, Australia; bNational High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310-4005; cDepartment of Biogeochemistry, Japan Agency for Marine–Earth Science and Technology, 237-0061 Kanagawa Prefecture, Yokosuka, Natsushimacho, Japan; dGeoscience Australia, Symonston, ACT 2609, Australia; and eDepartment of Geology, Unité de Recherche Geology, University of Liège, 4000 Liege, Belgium Edited by Andrew H. Knoll, Harvard University, Cambridge, MA, and approved June 8, 2018 (received for review March 6, 2018) The average cell size of marine phytoplankton is critical for the the molecular fossils of biological lipids, can provide comple- flow of energy and nutrients from the base of the food web to mentary information about primary producers. For example, higher trophic levels. Thus, the evolutionary succession of primary hydrocarbon fossils of carotenoid pigments extracted from sed- producers through Earth’s history is important for our understand- imentary rocks have been used to detect phototrophic green ing of the radiation of modern protists ∼800 million years ago and (Chlorobiaceae) and purple sulfur bacteria (PSB) (Chromatia- ∼ the emergence of eumetazoan animals 200 million years later. ceae) in 1,640-My-old marine ecosystems (4, 5), while the con- Currently, it is difficult to establish connections between primary centration of eukaryotic steranes, relative to bacterial hopanes, production and the proliferation of large and complex organisms may provide basic information about the ecological relevance of because the mid-Proterozoic (∼1,800–800 million years ago) rock Precambrian algae (6). -
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.