Absorption Spectrum Of Chlorophyll Research Articles

Analyses of absorption and fluorescence spectra of water-soluble chlorophyll proteins, pigment System II particles and chlorophyll a in diethylether solution by the curve-fitting method

Absorption and fluorescence spectra in the red region of water-soluble chlorophyll proteins, Lepidium CP661, CP663 and Brassica CP673, pigment System II particles of spinach chloroplasts and chlorophyll a in diethylether solution at 25°C were analyzed by the curve-fitting method (French, C.S., Brown, J.S. and Lawrence, M.C. (1972) Plant Physiol. 49, 421–429). It was found that each of the chlorophyll forms of the chlorophyll proteins and the pigment System II particles had a corresponding fluorescence band with the Stokes shift ranging from 0.6 to 4.0 nm. The absorption spectrum of chlorophyll a in diethylether solution was analyzed to one major band with a peak at 660.5 nm and some minor bands, while the fluorescence spectrum was analyzed to one major band with a peak at 664.9 nm and some minor bands. A mirror image was clearly demonstrated between the resolved spectra of absorption and fluorescence. The absorption spectrum of Lepidium CP661 was composed of a chlorophyll b form with a peak at 652.8 nm and two chlorophyll a forms with peaks at 662.6 and 671.9 nm. The fluorescence spectrum was analyzed to five component bands. Three of them with peaks at 654.8, 664.6 and 674.6 nm were attributed to emissions of the three chlorophyll forms with the Stokes shift of 2.0–2.7 nm. The absorption spectrum of Brassica CP673 had a chlorophyll b form with a peak at 653.7 nm and four chlorophyll a forms with peaks at 662.7, 671.3, 676.9 and 684.2 nm. The fluorescence spectrum was resolved into seven component bands. Four of them with peaks at 666.7, 673.1, 677.5 and 686.2 nm corresponded to the four chlorophyll a forms with the Stokes shift of 0.6–4.0 nm. The absorption spectrum of the pigment System II particles had a chlorophyll b form with a peak at 652.4 nm and three chlorophyll a forms with peaks at 662.9, 672.1 and 681.6 nm. The fluorescence spectrum was analyzed to four major component bands with peaks at 674.1, 682.8, 692.0 and 706.7 nm and some minor bands. The former two bands corresponded to the chlorophyll a forms with peaks at 672.1 and 681.6 nm with the Stokes shift of 2.0 and 1.2 nm, respectively. Absorption spectra at 25°C and at −196°C of the water-soluble chlorophyll proteins were compared by the curve-fitting method. The component bands at −196°C were blue-shifted by 0.8–4.1 nm and narrower in half widths as compared to those at 25°C.

Studies on the absorption spectra of chlorophyll a in aqueous dispersions of lipids from the photosynthetic membranes

Studies on the absorption spectra of chlorophyll a in aqueous dispersions of lipids from the photosynthetic membranes

SPECTROSCOPY OF CHLOROPHYLL IN BIOLOGICAL AND SYNTHETIC SYSTEMS*

Abstract. –This review discusses recent spectroscopic studies aimed at discovering the structure, orientation, and function of chlorophyll in vivo. In plant membranes there appear to be at least two distinct types of chlorophyll a. The greater part, over 99%, is antenna chlorophyll which absorbs and transfers radiant energy to a few specialized chlorophyll molecules in a reaction center where the actual charge separation occurs.A dimer‐oligomer model for antenna chlorophyll has been proposed on the basis of comparative studies of the absorption spectra of chlorophyll in various dry solvents and in vivo. Unfortunately a similarity between essentially structureless broad spectra is very weak evidence for their original identity. Also the requirement of an anhydrous environment for most of the chlorophyll in biological material is an unlikely postulate. A cross‐linked, linear polymer model of chlorophyll in vivo has also been proposed. Recent Resonance Raman spectroscopic results appear to rule out, in large part, either polymer model and once again suggest that it is the various attachments of chlorophyll to proteins which determine its function as antenna pigment in vivo. Circular dichroism measurements of chlorophyll in various plant materials have also led to the conclusion that antenna chlorophyll has strong interaction with protein. However, some doubt still exists as to the interpretation of these CD results. New studies of fluorescence, polarized fluorescence and Resonance Raman spectroscopy of various plant species corroborate the original proposition, based upon deconvolution of absorption spectra, that antenna chlorophyll occurs in vivo in at least five discrete pools, and that each pool is likely to be located in the same environment in different plants.A new model‐systems approach to simulating chlorophyll in vivo has come through the use of lipid bilayers and liposomes. Charge transfer has been observed between chlorophyll in a lipid phase and phycobiliproteins or cytochrome c.The most promising, newly synthesized model for the reaction center, P700, is a covalently bound dimeric derivative of pyrochlorophyllide a. Its properties are similar to P700 in several respects except for reversible photooxidation which has not yet been observed. By detergent treatments chlorophyll‐protein complexes having about 20–40 chlorophyll a molecules for every P700 have been isolated from different plants, and their spectroscopic properties are under investigation in several laboratories. The several hypotheses to explain the shape of the oxidized minus reduced absorption difference spectrum of P700 have not yet been reconciled. The nature of the photosystem II reaction center chlorophyll, P680, is also a subject of active investigation. Its absorption difference spectrum appears to have two kinetic components.

The effect of heavy metals on some aspects of lichen physiology

The effect of the heavy metals cadmium, cobalt, copper, lead, mercury, nickel, and silver on the lichen Umbiliearia muhlenbergii (Ach.) Tuck, is described in terms of membrane integrity, chlorophyll damage, and changes in photosynthetic 14C fixation. Increasing concentrations of copper, mercury, and silver produced a gradual potassium loss from the thallus while the other metals tested initiated an abrupt efflux at a specific concentration. Copper, mercury, and silver caused both a displacement and a decrease in the absorption spectrum of chlorophyll, whereas no detectable changes were induced by the other metals. The relative toxicities of these metals on photosynthesis is reflected in the series Ag. Hg > Co > Cu, Cd > Pb, Ni for short-term exposures, and Ag. [Formula: see text] for extended exposures. The tendency for the metals studied to fall into two distinct groups on the basis of their effects on lichen metabolism is discussed in terms of their physicochemical properties.

An analysis of the visible absorption spectrum of chlorophyll a monomer, dimer,and oligomers in solution.

An analysis of the visible absorption spectrum of chlorophyll a monomer, dimer,and oligomers in solution.

New chlorophyll- b forms in a chlorophyll-detergent photosynthetic model system

The absorption spectra of chlorophyll b in Triton X-100 micelles at room temperature are superpositions of components with absorption maxima at 640.8, 648.9, 659.5, 669.6, 682.1 and 695.7 nm, obtained from Gaussian analysis of the spectra. The last four forms strongly overlap the chlorophyll a forms of this system obtained with maxima at 659.3, 667.6, 674.3, 680.8, 686.5, 692.8, 701.9, 713.6 and 722.0 nm. Since the in vivo chlorophyll a forms practically coincide with the forms found in this system, the possible existence of in vivo overlapping chlorophyll b and a forms eventually should be taken into consideration. In this case, however, the Gaussian analysis of in vivo absorption bands in itself in the proper spectrum range cannot discriminate between chlorophyll a and b components.

The absorption spectrum of chlorophyll a and the chlorophyll/dioxane and chlorophyll/benzoquinone interactions

A molecular orbital calculation, using the “free-electron-network” method, is reported for the absorption spectrum of chlorophyll a and the complexes chlorophyll/ p-dioxane and chlorophyll/ p-benzoquinone. For chlorophyll a, our results are in good agreement with experiment and are substantially the same as those obtained by Weiss using the self-consistent molecular-orbital method. Our results seem to indicate: (i) that chlorophyll a has 26 rather than 28 π electrons, (ii) that, in a chlorophyll complex, the central magnesium atom has a coordination number of 6, and (iii) that the chlorophyll/benzoquinone complex has an intense absorption band centered at 713 nm. If present in vivo this complex can provide a model for the P-700 energy trap.

An analysis of flash-induced electrical transients of a BLM containing chloroplast lamella extracts

The electrical transients produced by chloroplast bilayer lipid membranes (Chl-BLM) from flash excitation are seen to result from three photocurrents and a discharge current. Each of the three photo-initiated charge transports in Chl-BLM (designated as Components A, B and C) exhibits an action spectrum similar to chlorophyll absorption spectra. The fast components (A and B), which are induced by electron acceptors such as Fe+3, have rise-times of ∼3 μsec and ∼20 msec, and occur in TLM (thin lipid membranes, i.e., colored membranes up to ∼1 μ thick) as well as in BLM. Component C is induced by a transmembrane pH difference or applied voltage, has a rise-time of ∼1 sec, and occurs only in BLM. Component C is associated with exciton dissociation and proton transport. The mobility of the Component A current carriers in TLM is estimated to be about 1×10−2 cm2/volt sec, and are, hence,electronic. The photovoltage waveforms are described by equations developed, which consider Component A as being caused by a direct charge separation proportional to the illumination intensity (within ≳0.5 μsec), and Components B and C being caused by two types of exciton processes which cause charge transport after the illumination period.

Über den Ureidstoffwechsel beim Laubmoosprotonema von Funaria hygrometrica L. (Sibth.): I. Der Einfluß vou verschiedenfarbigem Licht

1. Allantoin and allantoic acid were about 6 % of the total nitrogen content of moss protonema ( Funaria hygrornetica L.). 2. The level of endogenous allantoin depends on the spectrum colour of the irradiation. The peaks coincide with the peaks of a chlorophyll absorption spectrum from a methanolic extract of moss protonema. 3. The total amount of allan to in consists of two parts. One part is supplied by metabolism in darkness but the main one depends on light. Green- and far red light are “physiological dark conditions” for the moss protonema. In the dark ureide degradation comes to an end with allantoic acid. There are only traces of urea. 4. The coinciding correlations between the levels of allantoin and chlorophyll as the influences of inhibitors (DCMU, Salicylaldoxime, Cycloheximide, 2, 4 DNP, Chloramphenicol) are every reason to believe that the chloroplasts are the regulating organelles of the ureide metabolism.

The Pi electron structure and absorption spectra of chlorophylls in solution

The Pi electron structure and absorption spectra of chlorophylls in solution

Polarised absorption spectroscopy of chlorophyll-lipid membranes

A technique has been developed for measuring visible absorption spectra of chlorophyll in lipid membranes. An expression is derived which enables the directions of the transition moments of the different absorption bands to be determined from polarisation data. It is found that the transition moments of the principal blue and red absorption bands of chlorophyll a make angles of 26° and 36.5° respectively with the plane of the membrane. On the assumption that these two transitions lie in the plane of the porphyrin ring and are mutually perpendicular, it may be deduced that the plane of the porphyrin ring is tilted at approx. 48° to the membrane surface. For chlorophyll b the transition moments of the blue and red bands are found to make angles of 29.5° and 36.5° with the plane of the bilayer, giving an angle of tilt of the porphyrin ring of approx. 51°. These results are compared with measurements of dichroism in vivo.

Fluoride injury symptoms in epiphytic lichens and mosses

This study was conducted in Arvida, Quebec, where volatile fluorides and HF are released into the atmosphere from an aluminum factory. Lichen and moss-bearing bark discs, cut out from trees in an unpolluted area, were fixed in groups of six in rectangular wooden boards. All discs were photographed in color as well as in black and white. Fifteen sites, in addition to a control site, were selected in different directions from the factory. At each site two boards were fixed with nails in a vertical position at a height of 8–10 m on a tree. One board was removed after 4 months exposure and the other after 12 months. The lichens and mosses exposed in control and polluted areas were compared with respect to their color, external morphology, plasmolysis in algal cells, loss of green color, the nature of reactions towards neutral red and 2,3,5-triphenyl-2H-tetrazolium chloride (TTC), absorption spectra of chlorophyll, and fluoride concentration. Results indicate that F-pollution affects moisture balance, causes chlorophyll damage, and produces other symptoms of injury which could lead to ultimate death of these organisms.

A study of chlorophyll bin vivo

1. The absorption spectrum of chlorophyll b in vivo at 77°K is presented as the difference spectrum between preparations of spinach and chlorophyll b-free Vischeria stellata chloroplasts. 2. A shoulder on this spectrum around 662 nm is due to a component different from chlorophyll b. This component may well be identical with the chlorophyll a form, chlorophyll a (665). 3. The 77°K chlorophyll b absorption spectra in the nonfractionated photosyn-thetic pigment apparatus and in fractions mainly representing Photosystems 1 or 2 are not significantly different. 4. The aerobic irreversible photobleaching of chlorophyll b was studied in the intact pigment complex as well as in fractions mainly consisting of Photosystem 1 or 2. A two-step photobleaching was observed in all cases. The time-course of this bleaching was not significantly different for chlorophyll b in both fractions. 5. These results do not indicate that more than a single chlorophyll b complex occurs in vivo.

Action Spectra for Photosystems I and II in Formaldehyde Fixed Algae

Action spectra were obtained for photosystems I and II in chemically fixed algal cells and for photosystem I in unfixed lysozyme treated cells. Untreated algal cells yielded neither of the 2 light reactions with the reaction mixtures used. The action spectra for photosystem I in the blue-green alga Anacystis nidulans and red alga Porphyridium cruentum follow the absorption spectrum of chlorophyll a with a small peak in the region of the accessory pigments. In the green alga Chlorella pyrenoidosa the photosystem I action spectrum follows the absorption spectrum of chlorophyll a. Photosystem II action spectra in A. nidulans and P. cruentum follow the absorption spectra of the accessory pigments while that in C. pyrenoidosa is shifted slightly toward the blue spectral region. These results provide additional evidence that formaldehyde fixed cells are valid models for studying the light reactions of photosynthesis.

SOME SPECTRAL CHARACTERISTICS OF CHLOROPHYLLcFROMTRIDACNA CROCEAZOOXANTHELLAE

Absorption spectra of chlorophyll c prepared from Tridacna zooxanthellae (and now known to be the component chlorophyll c2) were scrutinized with special attention to the ratio of the Soret to the red band in methanol and acetone and the spectral changes resulting from the addition of water, acid and alkali. The band ratios of the chlorophyll c preparation determined with methanol and with acetone as the solvent were 9.4, but the ratios determined in aqueous mixtures of these organic solvents were appreciably lower than this value, which was interpreted as due to polymerization of chlorophyll c molecules. When chlorophyll c in aqueous acetone was acidified with HC1, the spectrum was changed to a spectrum with a sharp Soret band which is regarded as the spectrum of pheophytin c. When acidified in aqueous methanol, however, the Soret band dropped remarkably, being accompanied first by a slight shift of band to longer wavelengths and next by a greater shift to shorter wavelengths. These two steps of band shifts were interpreted as due to dimerization and further polymerization of dimeric chlorophyll c, respectively. The alkaline hydrolysis with NaOH and that with ammonia gave different spectra. These spectral characteristics of chlorophyll c, isolated from Tridacna crocea zooxanthellae, will help to resolve controversies over the spectral properties of this pigment, especially those caused by unrecognized polymerization.

Water soluble spinach chloroplast chlorophyll-protein complexes prepared without added detergents or organic solvents

Two water soluble chlorophyll-protein complexes were obtained from spinach chloroplast thylakoids without the aid of added detergents or organic solvents. One complex contained the pigments chlorophyll a & b and the quinones vitamin K 1, tocopherolquinone, and a plastoquinone while the other contained in addition a second plastoquinone and the pigments lutein, violaxanth and neoxanthin. Both complexes showed a tendency to aggregate during purification; however, a crude mixture of these two complexes had an average apparent sedimentation coefficient (S 20,w) of 5.6 S. The chlorophyll absorption spectrum of the combined complexes was very similar to that of the chlorophylls in vivo . The red absorption maximum for chlorophyll a was at 679 mμ and that for chlorophyll b was at 652 mμ.

Low Temperature Absorption Spectra of Chlorophyll a in Polar and Nonpolar Solvents

Absorption spectra of chlorophyll a were measured in polar and non-polar solvents, as a function of temperature from 298 degrees to 77 degrees K. Both dilute and concentrated solutions were examined. In both types of solvents at room temperature, the absorption spectra of concentrated solutions differ from dilute ones in that the half width of the main red absorption band is greater, and all bands are shifted to longer wavelengths. These differences are largely due to the presence of dimers when the pigment concentration is high. In dilute ethanol solutions, where the chlorophyll is unassociated, cooling causes a red shift in all bands which is due to the increased polarity of the solvent at low temperature. On cooling at high concentrations in ethanol and EPA, a new band appears near 700 nm. This band is attributed to dimers present prior to cooling, but absorbing at shorter wavelengths at room temperature. In nonpolar solvents, a band near 700 nm appears at the solvent freezing point. In these solvents, the "700" nm absorption is attributed to dimers, and/or small polymers, partly formed by cooling. A change in aggregate geometry when the solvent becomes viscous or frozen can account for the appearance of this "700" nm absorption band at low temperature, in polar and nonpolar media.

Action Spectra for the Transient and the Normal Photosynthetic Oxygen Evolution in Wheat Leaves

AbstractAn action spectrum within the wavelength region 430–700 nm has been determined for an oxygen Iransient isolated from the main photosynthetic oxygen evolution in wheat leaves. the spectrum follows the absorption spectrum of chlorophyll b.In order to compare this oxygen evolving process with the normal photosynthetic oxygen evolution, an action spectrum for this later process was also determined but only in the wavelength region 600–700 nm. This action spectrum closely corresponds to other action spectra for the photosynthetic oxygen evolution found in the literature.The behaviour of the oxygen transient after various treatments was also studied. It was found that the transient oxygen evolution was influenced by the dark period between irradiations, and by a previous irradiation with a wavelength longer than 695 nm, both conditions having a promoting effect on the oxygen evolution.The action spectra and the other findings are discussed on the basis of the two‐pigment hypothesis.

Changes with age in the absorption spectrum of chlorophyll a in a diatom.

Absorption spectra of a young and an old culture of the diatom Pheodactylum tricornutum were measured in thin layers between two opal glass sheets. The spectra at 24° and at -196°C were replotted to give equal areas from 730–625 mμ to allow direct comparison. At 24°C the spectrum for the difference between the two cultures had a negative component of 18 mμ half width centered at 675 mμ and a positive region of W0.5=26 mμ near 700 mμ. The spectra at -196°C may be somewhat distorted by clumping of the cells during freezing but nevertheless the 16 day culture clearly showed a smaller proportion of Ca “670” to Ca “680”. This older culture has a shoulder due to a 707 mμ component. The difference curve at -196°C shows the decrease of an unsymmetrical band peaking at 669 mμ and an increase at 695 mμ in addition to the 707 mμ component. Due to the possibility of distortion, the presence of an actual component at 695 is doubtful in these particular cultures. The room temperature spectrum in the chloropyhll a region for the 5 day culture can be closely fitted by a single probability curve at 675 mμ having a half-width of 31 mμ. The sum of two components, with widths more reasonable for chlorophylls, also matched the data well enough. These two probability curves, of 22 mμ half width, centered on 669 and 683.2 mμ and had a height ratio, h669/h683 of 1.18. In the 16 day culture the ratio for these bands changed to 1.11 and there was extra absorption around 700 mμ.

Spectrophotometric characteristics of chlorophylls a and b and their pheophytins in ethanol.

Abstract The absorption spectra of chlorophylls a and b in 96% ethanol, and of pheophytins a and b in 80% ethanol-0.01 N hydrochloric acid have been determined in comparison with known absorption coefficients.