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Featured researches published by Werner Wehrmeyer.


Biophysical Journal | 1990

Studies on chromophore coupling in isolated phycobiliproteins: III. Picosecond excited state kinetics and time-resolved fluorescence spectra of different allophycocyanins from Mastigocladus laminosus

Alfred R. Holzwarth; Edith Bittersmann; Wolfgang Reuter; Werner Wehrmeyer

The excited state kinetics of three different allophycocyanin (AP) complexes has been studied by picosecond fluorescence spectroscopy. Both the fluorescence kinetics and the decay-associated fluorescence spectra of the different complexes can be understood on the basis of a structural model for AP which uses (a) an analogy to the known x-ray determined structure of C-phycocyanin, (b) the biochemical analogies of AP and C-phycocyanin, and (c) the biochemical composition of AP-B (AP-681). A model is developed that describes the excited state kinetics as a mixture of internal conversion processes within a coupled exciton pair and energy transfer processes between exciton pairs. We found excited state relaxation times in the range of 13 ps (AP with linker peptide) up to 66 ps (AP-B). The trimeric aggregates AP 660 and AP 665 show one fast relaxation component each, as was expected on the basis of their symmetry properties. The lower symmetry of AP-B (AP-681) gives rise to two fast lifetime components (tau(1) = 23 ps and tau(2) = 66 ps) which are attributed to internal conversion and/or energy transfer between excitonic states formed by the coupling of symmetrically and spectrally nonequivalent chromophores. It is proposed that the internal conversion between exciton states of strongly coupled chromophores fulfills the requirements of the small energy gap limit. Thus, internal conversion rates in the order of tens of picoseconds are feasible. The influence of the interaction of the linker peptide on the properties of the AP trimer are manifested in the fluorescence kinetics. Lack of the linker peptide in AP 660 gives rise to a heterogeneity in the chromophore conformations and chromophore-chromophore interactions.


Biochimica et Biophysica Acta | 1984

Picosecond time-resolved energy transfer in phycobilisomes isolated from the red alga Porphyridium cruentum☆

Joachim Wendler; Alfred R. Holzwarth; Werner Wehrmeyer

Abstract Energy-transfer kinetics in isolated phycobilisomes of the red alga Porphyridium cruentum has been probed by picosecond absorption and fluorescence techniques upon selective excitation of the individual phycobiliproteins by a tunable picosecond laser. The fluorescence decays of B-phycoerythrin and R-phycocyanin were found to be non-exponential. It does not, however, follow an exp (− 2At 1 2 ) decay law. The main components in the fluorescence decays of B-phycoerythrin and R-phycocyanin have lifetimes of approx. 60 and approx. 40 ps, respectively, as a result of energy transfer. In addition a second decay component with small relative amplitude is required for a good description of the energy-transfer kinetics. This component has a lifetime in the range of approx. 200 ps (B-phycoerythrin) and 550 ps (R-phycocyanin). The fluorescence decay in the main emission band is non-uniform with two components of 1.0 and 1.8 ns. The energy transfer processes were found to occur sequentially from B-phycoerythrin to R-phycocyanin and allophycocyanin, in agreement with an earlier study (Searle, G.F.W., Barber, J., Porter, G. and Tredwell, C.J. (1978) Biochim. Biophys. Acta 501, 246–256). Measurements of transient absorption anisotropy revealed the presence of two processes leading to fast depolarization in B-phycoerythrin. The anisotropy decay times have values of 12 and 150 ps. The shorter one is attributed to intramolecular energy transfer within B-phycoerythrin monomers. the longer one either arises from transfer within the B-phycoerythrin pigment bed or is related to the transfer from B-phycoerythrin to R-phycocyanin. Rising-terms are observed in the fluorescence kinetics of the indirectly excited pigments. Their rate constants agree well with those determined from the decay of the directly excited pigments. The characteristic energy-transfer time from B-phycoerythrin at the periphery to the terminal emitter is around 70 ps. This fast transfer ensures an efficiency of better than 98%. The overall energy-transfer kinetics in these hemiellipsoidal phycobilisomes is found to be very similar to that found in hemidiscoidal phycobilisomes.


FEBS Journal | 1978

Biliprotein Assembly in the Disc-Shaped Phycobilisomes of Rhodella violacea

Klaus‐P. Koller; Werner Wehrmeyer; Erhard Mörschel

Heterogeneous complexes with a molecular weight of about 790000 containing B-phycoerythrin (Bangiales phycoerythrin) and C-phycocyanin (Cyanophyceae phycocyanin) in a molar pigment ratio of 2:1 were isolated from purified, dissociated phycobilisomes. Electron microscopical investigations revealed structures of three discs aggregated face to face with an apparent distance of 1.5 nm between each disc. Two discs may represent phycoerythrin and one phycocyanin. The complexes are structurally identical with tripartite units of the phycobilisome periphery. Fluorescence data confirmed the integrity of isolated tripartite units. Excitation at 546 nm gives a fluorescence maximum at 644 nm, indicating intermolecular transfer of excitation energy from phycoerythrin to phycocyanin. Comparative subunit analyses and spectral data suggested that no allophycocyanin is present. Cross-linking experiments gave evidence for a polar arrangement of phycocyanin within the complex. This pigment itself is an aggregate of two smaller molecules each having a molecular weight of about 140000. Tripartite units contain all the phycoerythrin and phycocyanin of the phycobilisome. On this basis, a phycobilisome model is proposed which combines the aspects of biliprotein distribution, energy transfer and fine structure.


Photochemistry and Photobiology | 1982

PICOSECOND TIME RESOLVED ENERGY TRANSFER IN ISOLATED PHYCOBILISOMES FROM RHODELLA VIOLACEA (RHODOPHYCEAE)

Alfred R. Holzwarth; Joachim Wendler; Werner Wehrmeyer

Energy‐transfer kinetics in isolated phycobilisomes (PBS) of the red alga Rhodella violacea have been measured by detecting both ground state recovery and fluorescene rise or decay using a synchronously pumped cavity‐dumped dye laser as excitation source. For the first time the constituent phycobiliproteins of PBS have been excited selectively, thus allowing the kinetics of both directly and indirectly excited pigments to be followed. Energy‐transfer between the phyeobiliproteins, which was found to proceed extremely fast, is governed by nonexponential kinetics at low excitation intensities. When analyzed in a biexponential model, the main components of the fluorescence of B‐phycoerythrin (B‐PE) and C‐phycocyanin (C‐PC) decay with τ= 34 ps and τ= 25 ps, respectively. Evidence is presented that transfer between the biliprotein pigments is close to a single‐step process with some contribution of homotransfer. Fluorescence quantum yields of PBS have been determined as a function of the excitation wavelength and were found to reflect a dissociation equilibrium involving ca. 10% dissociated PBS at the concentrations studied.


Planta | 1986

Effects of nitrogen starvation on the function and organization of the photosynthetic membranes in Cryptomonas maculata (Cryptophyceae)

E. Rhiel; K. Krupinska; Werner Wehrmeyer

Nitrogen deficiency affects both photosystems and the antennae pigment systems in the photosynthetic apparatus of the marine alga, Cryptomonas maculata. Under increasing energy fluence rates, O2 evolution in nitrogen-deficient (-N) cell suspensions never reached a positive value; in control cultures (+N), O2 evolution increased and was saturated at about 6.4 W·m-2 with about 100 μmol O2·mg chlorophyll-1·h-1. During fluorescence-induction experiments at room temperature, Fo and Fmax were significantly increased in-N cells whereas the Fvar/Fmax ratio decreased from 0.6 to 0.1. These observations can be correlated with a significantly decreased population of 12.5-nm-size particles in the exoplasmic-fracture (EF) faces of freeze-cleaved thylakoid membranes in-N cells (Rhiel et al., 1985, Protoplasma 129, 62–73). The EF particles are suggested to represent photosystem II associated with chlorophyll a/c-protein complexes (LHCP). The banding pattern of isolated and Triton X-100-solubilized thylakoid membranes of both +N and-N cells in sucrose gradients showed that the LHCP is still present in-N cells. The same applies to sodium dodecyl sulfate-polyacrylamide gel electrophoresis of these membrane fractions. The reduced number of the 12.5-nm particles in the EF faces of-N cells may be a result of decoupling of the LHCP constituents of the photosystem-II complex rather than their degradation. This is supported by high values for the initial fluorescence Fo in fluorescence-induction experiments and, in part, is indicated by the shift of the maximal fluorescence emission from 693 nm in +N to 684 nm in-N cells. The lack of the CP1 band in the gels of sodium dodecyl sulfate-solubilized thylakoid membranes from-N cells after electrophoresis demonstrates that photosystem I is also severely affected.


Archives of Microbiology | 1975

Cryptomonad biliprotein: phycocyanin-645 from a Chroomonas species.

Erhard Mörschel; Werner Wehrmeyer

The properties of phycocyanin-645 from the fresh water cryptomonad Chroomonas spec. were investigated after the pigment was isolated and purified by a combination of differential ammonium sulphate fractionation, gel filtration chromatography and ammonium sulphate gradient elution.Phycocyanin-645 is characterized by absorption maxima at 645 nm, 584 nm, 369 nm, 275 nm and shoulders at 340 nm and 620 nm. The CD spectrum has a negative maximum at 645 nm and a positive maximum at 584 nm with a shoulder at 610 nm.The fluorescence emission spectrum is asymmetrical and shows a maximum at 660 nm and a shoulder at approximately 715 nm. The molecular weight of the native phycocyanin-645, estimated by gel filtration, is 45000 for all multiple pigment forms below.Phycocyanin-645 is heterogenous in charge as revealed by isoelectric focusing with pIs at 7.03, 6.17, 5.75, 5.25 and 4.88, respectively, the main bands lying at pI 7.03 and pI 6.17. This was confirmed by polyacrylamide gel electrophoresis; five pigment components differing in mobility were found. We propose the term “multiple pigment forms” for these five phycocyanin-645 modifications.Calibrated SDS gel electrophoresis shows phycocyanin-645 to consist of three subunits, two light chains (α1, α2), having molecular weights of 9200 and 10400, respectively, and one heavy chain (β), having a molecular weight of 15500. Suggesting a 1:1:2 ratio between the subunits, the quaternary structure of the pigment molecule is α1β1-α2β1.


Planta | 1980

Isolation and Biliprotein Characterization of Phycobilisomes from the Thermophilic Cyanobacterium Mastigocladus laminosus Cohn

Michael Nies; Werner Wehrmeyer

A method for the effective isolation of functionally intact phycobilisomes from the thermophilic cyanobacterium M. laminosus is presented, using an unconventional high buffer molarity for stabilizing the aggregates and introducing a DNAse treatment of the disrupted cells to obtain sharp banding of the phycobilisomes in the linear sucrose density gradients.The structural integrity of the isolated phycobilisomes is demonstrated by a fluorescence emission maximum at 673 nm of aggregated allophycocyanin and by electron microscopy.Besides C-phycocyanin and allophycocyanin, phycoerythrocyanin is a constituent pigment of the phycobilisomes. These pigments indicated in the absorption spectrum of phycobilisomes with a maximum at 610 nm and two shoulders at 650 and 580 nm, respectively, were characterized by spectral data and isoelectric points.


Biochimica et Biophysica Acta | 1983

Studies on chromophore coupling in isolated phycobiliproteins. I. Picosecond fluorescence kinetics of energy transfer in phycocyanin 645 from Chroomonas sp.

Alfred R. Holzwarth; Joachim Wendler; Werner Wehrmeyer

Abstract By applying the single-photon timing method the fluorescence kinetics of phycocyanin 645 from Chroomonas sp. has been measured as a function of both the excitation and emission wavelength using low-intensity excitation. The fluorescence kinetics were found to be dominated by a fast (15 ps) and a slow (1.44 ns) decay component. The relative yields and amplitudes of these components depended strongly on both the excitation and emission wavelengths. A component with a small relative amplitude and a lifetime (τ) in the range of 360–680 ps has been found as well. The fast decay component is attributed to intramolecular energy transfer from sensitizing to fluorescing chromophores. Our results are discussed in relation to a chromophore coupling model suggested previously (Jung, J., Song, P.-S., Paxton, R.J., Edelstein, M.S., Swanson, R. and Hazen, E.E. (1980) Biochemistry 19, 24–32).


Archives of Microbiology | 1980

Biliprotein assembly in the disc-shaped phycobilisomes of Rhodella violacea electron microscopical and biochemical analyses of C-phycocyanin and allophycocyanin aggregates

Erhard Mörschel; Klaus‐Peter Koller; Werner Wehrmeyer

C-phycocyanin and allophycocyanin from the red alga Rhodella violacea were investigated by electron microscopy and biochemical methods using samples taken from the same fractions.The molecular weights of the native biliprotein aggregates C-phycocyanin and allophycocyanin are about 139,000 (140,000) and 130,000 (145,000) as revealed by calibrated gel chromatography, gradient gel electrophoresis and morphological measurements on the basis of an average protein packing density. These molecular weights are direct evidence for a trimeric aggregation form (αβ)3 of these biliproteins. Independently, their monomers were determined to be about 34,400 (C-phycocyanin) and 33,900 (allophycocyanin).C-phycocyanin and allophycocyanin are ringshaped, six-membered, biliprotein aggregates with dimensions of about 10.2×3.0 nm and 10.0×3.0 nm, respectively. The aggregates are made up of six subunits, 3α and 3β, which are assumed to be associated in alternating positions. They are arranged in regular hexagons in C6 symmetry. Hexameric aggregates (αβ)6, so far only isolated for C-phycocyanin, originate by face to face association of two trimeric aggregates.


Archives of Microbiology | 1970

Zur Feinstruktur der Chloroplasten einiger photoautotropher Cryptophyceen

Werner Wehrmeyer

SummaryThe ultrastructure of the chloroplasts and pyrenoids of each one species of the genera Cryptomonas, Chroomonas, and Hemiselmis (Cryptophyceae) was investigated by electron microscopy. The thylakoids are loosely associated mainly in pairs, separated by a slight space of 30–80 Å. One thylakoid can be associated with one and the same thylakoid for a longer distance or in alternation with two thylakoids on opposite sides. Bifurcated thylakoids were observed in all three species.Deviating from all known chloroplasts the thylakoids of the Cryptophyceae, investigated here, are electron opaque, containing a fine granular, dense material, dispersed in the intrathylakoidal space (=loculus in the terminology of Weier, 1962). Caused by a varying distribution of the intrathylakoidal material the thickness of the thylakoids changes in the range of 190–300 Å in Cryptomonas and of 240 to 360 Å in Hemiselmis and Chroomonas; club-shaped parts at the end of the thylakoids can even exceed these values.Ribosome-like particles, 120–180 Å in diameter, vacuoles, and scattered electron-transparent DNA-containing areas were observed in the chloroplast matrix, but no granular fraction corresponding to the biliprotein particles of the Rhodophyceae or Cyanophyceae associated with the surface of the thylakoid membranes could be detected.The stalked pyrenoids of Hemiselmis and Chroomonas are bulging of the anterior end of the boat-shaped chloroplast traversed by two associated thylakoids. In Cryptomonas the pyrenoid occupies the central part of the H- or U-shaped chloroplast, thus being a part of the connection of the two lobes. Paired thylakoids penetrate the bridge and terminate in the pyrenoid basis. On its free face the pyrenoid is bisected by a groove containing the stigma. The pyrenoids are surrounded by starch grains which lie outside the chloroplast envelope, yet, they are enclosed together with the stigma and the whole chloroplast by a periplastidal ER-cisterna, which usually is in continuity with the nuclear envelope.Zusammenfassung1.Die Feinstruktur der Chloroplasten und Pyrenoide von je einer Art der Gattungen Cryptomonas, Chroomonas und Hemiselmis (Cryptophyceae) wurden elektronenmikroskopisch untersucht.2.Die Thylakoide sind locker assoziiert, hauptsächlich zu zweit, und durch einen geringen Abstand von 30–80 Å getrennt. Ein Thylakoid kann für eine längere Strecke mit ein und demselben Thylakoid assoziiert sein oder im Wechsel mit zwei auf gegenüberliegenden Seiten verlaufenden Thylakoiden. Thylakoidgabelungen wurden in allen 3 Arten beobachtet.3.Abweichend von allen bekannten Chloroplasten sind die Thylakoide der hier untersuchten Cryptophyceen kontrastreich; sie enthalten im intrathylakoidalen Raum (=Loculus im Sinne von Weier, 1962) verteilt ein fein granuliertes, dichtes Material. Bedingt durch eine ungleiche Verteilung dieses intrathylakoidalen Materials wechselt die Dicke der Thylakoide im Bereich von 190–300 Å bei Cryptomonas und von 240–360 Å bei Hemiselmis und Chroomonas; keulenförmige Endglieder der Thylakoide können diese Werte noch übertreffen.4.Ribosomenähnliche Partikel von 120–180 Å Durchmesser, Vacuolen und verstreut vorkommende, elektronentransparente DNS-führende Bezirke wurden in der Chloroplastenmatrix beobachtet, jedoch konnte keine Granulafraktion entdeckt werden, die in enger Bindung an die Oberflächen der Thylakoidmembranen den Biliproteinpartikeln von Rhodophyceen und Cyanophyceen entsprechen würde.5.Die gestielten Pyrenoide von Hemiselmis und Chroomonas entspringen dem Vorderende des bootförmigen Chloroplasten und werden von einem Thylakoidpaar durchzogen. In Cryptomonas nimmt das Pyrenoid den zentralen Teil des H-oder U-förmigen Chloroplasten ein und stellt damit einen Teil der Verbindung der beiden Lappen dar. Gepaarte Thylakoide dringen bis in diese Brücke vor und enden in der Pyrenoidbasis. Auf der freien Seite ist das Pyrenoid durch einen Spalt aufgeliedert, der das Stigma enthält. Die Pyrenoide werden von Stärkekörnern umgeben, die außerhalb der Chloroplastenhülle liegen, die jedoch ihrerseits zusammen mit dem Stigma und dem ganzen Chloroplasten von einer periplastidären ER-Cisterne umschlossen werden, die gewöhnlich mit der Kernhülle in Zusammenhang steht.

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