Copper enzymes in isolated chloroplasts. polyphenoloxidase in beta vulgaris
TL;DR: Evidence that a copper enzyme, polyphenoloxidase (otherwise known as tyrosinase or catecholase), is localized in the chloroplasts of spinach beet (chard), Beta vu?garis is presented.
Abstract: The chloroplast, as the seat of chlorophyll pigments in plants, occupies a unique position in the economy of the green cell. In recent years there has been a renewed interest in the reactions and properties of chloroplasts as a result of the work of Hill (11, 12) and Hill and Scarisbrick (13, 14) who demonstrated that the reaction characteristic of photosynthesis in green plants, the evolution of oxygen, occurs in appreciable quantities in isolated chloroplasts under the influence of light and in the presence of suitable oxidants (2, 7, 8, 26). In the course of an investigation of oxygen evolution by isolated chloroplasts it was deemed important to explore their enzymatic composition. Of special interest were considered enzymes capable of participating in oxidation-reduction reactions, and more particularly, those localized principally, if not entirely, in the chloroplasts. This paper presents evidence that a copper enzyme, polyphenoloxidase (otherwise known as tyrosinase or catecholase), is localized in the chloroplasts of spinach beet (chard), Beta vu?garis.
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TL;DR: In this article, the spectral characteristics and absorption coefficients of chlorophylls, pheophytins, and carotenoids were analyzed using a two-beam spectrophotometer.
Abstract: Publisher Summary This chapter presents detailed information on chlorophylls and carotenoids to give practical directions toward their quantitative isolation and determination in extracts from leaves, chloroplasts, thylakoid particles, and pigment proteins. The chapter focuses on the spectral characteristics and absorption coefficients of chlorophylls, pheophytins, and carotenoids, which are the basis for establishing equations to quantitatively determine them. Therefore, the specific absorption coefficients of the pigments are re-evaluated. This is achieved by using a two-beam spectrophotometer of the new generation, which allows programmed automatic recording and printing out of the proper wavelengths and absorbancy values. Several procedures have been developed for the separation of the photosynthetic pigments, including column (CC), paper (PC), and thin-layer chromatography (TLC) and high-pressure liquid chromatography (HPLC). All chloroplast carotenoids exhibit a typical absorption spectrum that is characterized by three absorption maxima (violaxanthin, neoxanthin) or two maxima with one shoulder (lutein and β-carotene) in the blue spectral region.
10,367 citations
TL;DR: In this paper, the extinction coefficients for chlorophylls a and b in diethylether (Smith, J.H. and Benitez, A.V., eds.), used in this paper as primary standards, were verified by magnesium determination using atomic absorbance spectrophotometry.
5,326 citations
TL;DR: New equations are presented for spectrophotometric determination of chlorophylls, based on revised extinction coefficients of chloropylls a, b, c1 and c2, which may be used for determining chlorophyLLs a and b in higher plants and green algae.
4,542 citations
TL;DR: It was found that the response of the rate of CO2 Assimilation to irradiance, partial pressure of O2, p(O2), and temperature was different at low and high intercellular p(CO2), suggesting that CO2 assimilation rate is governed by different processes at lowand high inter cellular p (CO2).
Abstract: A series of experiments is presented investigating short term and long term changes of the nature of the response of rate of CO2 assimilation to intercellular p(CO2). The relationships between CO2 assimilation rate and biochemical components of leaf photosynthesis, such as ribulose-bisphosphate (RuP2) carboxylase-oxygenase activity and electron transport capacity are examined and related to current theory of CO2 assimilation in leaves of C3 species. It was found that the response of the rate of CO2 assimilation to irradiance, partial pressure of O2, p(O2), and temperature was different at low and high intercellular p(CO2), suggesting that CO2 assimilation rate is governed by different processes at low and high intercellular p(CO2). In longer term changes in CO2 assimilation rate, induced by different growth conditions, the initial slope of the response of CO2 assimilation rate to intercellular p(CO2) could be correlated to in vitro measurements of RuP2 carboxylase activity. Also, CO2 assimilation rate at high p(CO2) could be correlated to in vitro measurements of electron transport rate. These results are consistent with the hypothesis that CO2 assimilation rate is limited by the RuP2 saturated rate of the RuP2 carboxylase-oxygenase at low intercellular p(CO2) and by the rate allowed by RuP2 regeneration capacity at high intercellular p(CO2).
4,385 citations
TL;DR: In this paper, specific absorption coefficients for individual carotenoids and chlorophylls a and b, as well as the E 1% 1cm values for combined carotensoids, have been (re)estimated using 6 solvents (80 % acetone, chloroform, diethyl ether, dimethyl formamide and methanol) using two different types of spectrophotometer (0.1-0.5 nm and 1-4 nm band pass resolution).
4,156 citations
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TL;DR: This paper deals with the estimation of chlorophyll in plant extracts by application of absorption coefficients of the isolated solid chlorophylla components, and the question of artifacts is automatically clarified.
3,897 citations
TL;DR: This paper is a report on the observed responses from a group of elements not generally credited with a function in plant nutrition, which suggested that these and other elements, if present in minute quantity, may favorably influence the growth of plants.
Abstract: A PREVIOUS paper (Arnon, 1937) reported that, in a preliminary experiment, molybdenum, chromium, and nickel improved the growth of barley plants in a culture solution supplied with ammonium salts as the sole source of nitrogen. This finding suggested that these and other elements, if present in minute quantity, may favorably influence the growth of plants. It was deemed advisable to test this possibility by arranging a number of chemical elements in groups and by observing how the addition of a given group affects the growth of plants in culture solutions. This paper is a report on the observed responses from a group of elements not generally credited with a function in plant nutrition. EXPERIMENTAL METHODS. -Lettuce and asparagus plants were grown in a basic culture solution of the following composition: NH,H,PO4, 0.001 M; KNO3, .006 M; Ca(NO0)2, .004 M; MgSO4, 0.002 M. All the salts except the C.P.-grade ammonium phosphate were purified from heavy metals by a special technique developed in this laboratory-a method to be described by P. R. Stout and the author in a later publication. In making up culture solutions, distilled water was used throughout. An iron solution containing 0.5 per cent FeSO4 and 0.4 per cent tartaric acid was added thrice weekly at the rate of approximately 0.6 cc. per liter of culture solution. The number of iron applications was later reduced to one a week. Three supplementary solutions, each containing different elements in minute quantity, were prepared. These solutions were designated as A4, B7, and C13, respectively. In each case, the numeral following the capital letter indicates the number of elements supplied. The A4 solution furnished boron, manganese, zinc, and copper, the four generally accepted as indispensable for plant growth (review by Hoagland, 1937). The basic culture solution supplemented with the A4 solution therefore furnished the plant with a seemingly complete list of essential elements. One cc. of the A4 solution was used for each liter of culture solution (unless otherwise indicated), giving a concentration of 0.5 ppm. B, 0.5 ppm. Mn, 0.05 ppm. Zn, and 0.02 ppm. Cu. The composition of the A4 solution in grams in 1 liter of water was: H,BO., 2.86; MnCl,. 4H20, 1.81; ZnSO4.7H20, 0.222; CuSo4.5H20, 0.079. The supplementary solution designated B7 contained the following seven elements: molybdenum, vanadium, chromium, nickel, cobalt, tungsten, and
317 citations
TL;DR: The results of this study will enable to determine the nature of the relationship between the oxidising enzymes and the intracellular haematin compounds, and this will help to elucidate at least one portion of the complicated respiratory mechanism, of the cell.
Abstract: The object of this paper is the study of the functional relationship between the intracellular haematin compounds and the oxidising enzymes such as dehydrases and oxidases. It was shown previously (1925-1927) that aerobic organisms contain a very widely distributed intracellular haematin pigment-cytochrome-which can undergo reversible oxidation and reduction without being destroyed. Being the only compound directly visible in the living cell, cytochrome gives us important indications, not only of its own activity but also of that of other components of the respiratory system of the cell. The present paper will first deal with the thermostable peroxidase of yeast and other cells, and with the true thermostable oxidases such as the indophenol oxidase of yeast and muscle cells and the polyphenol oxidase of potato. This will be followed by the study of intracellular haematin compounds, and especially of the effects of various factors on the oxidation and reduction of cytochrome. The results of this study will enable us to determine the nature of the relationship between the oxidising enzymes and the intracellular haematin compounds, and this will help to elucidate at least one portion of the complicated respiratory mechanism, of the cell.
236 citations
TL;DR: The hæmoglobin method, originally used by Hoppe-Seyler to demonstrate oxygen from green plants, has been applied to study the oxygen evolution of isolated chloroplasts exposed to light.
Abstract: THE high affinity for oxygen possessed by muscle haemoglobin suggested its use as a very sensitive spectroscopic method for detecting and measuring small quantities of oxygen1. This method has now been applied to study the oxygen evolution of isolated chloroplasts exposed to light. While being much less sensitive than the bacterial methods which have been successfully applied in the past, the haemoglobin method (originally used by Hoppe-Seyler to demonstrate oxygen from green plants) has the advantage of giving the measure of oxygen. A solution of haemoglobin containing 0.45 × 104 gm. atoms of iron per litre, is equivalent to 1 c.mm. of oxygen per c.c.; the degree of saturation can be determined spectroscopically with an accuracy of 5 per cent.
201 citations
TL;DR: Inman (1935) brought further evidence as to the enzymic nature of the process, and showed also that fresh green extracts of many phanerogams will evolve oxygen in light, using the bacterial mathod.
Abstract: The system concerned with the assimilation of carbon dioxide by the green plant has, under optimum conditions, an activity comparable with the highest rate of cellular respiration in animals. At the moment there is, in the case of animals, considerable knowledge of the subcellular chemical mechanisms which can be connected with respiratory activity. In the green plant, on the other hand, there is still no direct indication of a single chemical mechanism connected with carbon assimilation. As the oxygen output, apart from CO2 evolution is a guide in searching for systems connected with respiration, so might an oxygen output, apart from CO2 absorption, indicate mechanisms characteristic of photosynthetic activity in the plant. The subcellular evolution of oxygen under illumination has been known in the case of green plants for many years (Spoehr 1926). The effect, however, was always insignificant compared with the original photosynthetic activity of the cell. The oxygen could only be detected by using certain bacteria which show either motility or luminescence with traces of this gas. But to this method we owe the classical investigations of Engelmann (Spoehr 1926) who showed that in the living cell oxygen appeared in the neighbourhood of the illuminated chloroplast and the experiments on the isolated chloroplasts of Funaria hygrometrica by Haberlandt, who demonstrated the production of oxygen in light. Ewart (1896) confirmed and extended these results using other mosses and Selaginella helvetica ; in a phanerogam, Elodea , no oxygen could be observed to come from the isolated chloroplastes. The same problem was approached in a somewhat different manner by Molisch (1925). The leaves of many phanerogams were allowed to dry slowly in air and finally over a dehydrating agent. This produced a stable preparation which, if ground up in water, would show an evolution of oxygen in light which could be detected by the bacterial methods. Molisch showed that these preparations were thermolabile, indicating an enzymic process. Recently, the matter was taken up by Inman (1935) who confirmed the experiments of Molisch and showed also that fresh green extracts of many phanerogams will evolve oxygen in light, using the bacterial mathod. Inman brought further evidence as to the enzymic nature of the process, and, moreover, did not consider the oxygen evolved to represent photosynthesis but suggested that it was due to a limited store of oxygen-giving material.
143 citations