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21.
Hans-Erik Åkerlund Bertil Andersson Agneta Persson Per-Åke Albertsson 《生物化学与生物物理学报:生物膜》1979,552(2):238-246
The isoelectric points of unbroken chloroplast lamellae and various subchloroplast fractions, including a preparation of inside-out thylakoids, have been determined using aqueous two-phase systems containing dextran and charged polyethylene glycol. When the amounts of material in the top phase in a phase system with the positively charged trimethylamino polyethylene glycol are plotted against pH the curve intersects the corresponding curve obtained from phase systems with the negatively charged polyethylene glycol sulfonate. This cross-point can be correlated with the isoelectric point of the material.The cross-point for unbroken chloroplast lamellae was found to be around pH 4.7. Mechanical disintegration lowered the cross-point to around pH 4.4, probably because of exposure of new membrane surfaces. The disintegrated chloroplasts were fractionated by differential centrifugation to separate the grana and stroma lamellae. The stroma lamellae vesicles showed the same isoelectric point as the unbroken lamellae, while a cross-point at pH 4.3 was obtained for the grana-enriched fraction. For thylakoid membranes destacked under low salt conditions the cross-point was 0.3 pH unit lower than for membranes originating exclusively from the stroma lamellae. The most acidic cross-point (pH 4.1) was observed for the fraction enriched in inside-out grana thylakoids. It is suggested that the differences in isoelectric point between various subchloroplast fractions reflect a heterogeneous arrangement of surface charge along and across the thylakoid membrane. 相似文献
22.
Eva Eriksson Per-Åke Albertsson Göte Johansson 《Molecular and cellular biochemistry》1976,10(2):123-128
Summary Erythrocytes from various species have been partitioned in aqueous two-phase systems consisting of water, dextran, poly-(ethylene glycol), salt and buffer. The terminal hydroxyl groups of the latter polymer were esterified with palmitic, oleic, linoleic and linolenic acids, as well as with deoxycholic acid. In a two-phase system containing unesterified poly(ethylene glycol) the erythrocytes are exclusively in the dextran-rich lower phase. When the poly(ethylene glycol) is esterified the red blood cells collect at the interface and/or in the poly(ethylene glycol)-rich upper phase depending on the type and concentration of esterified acid. Palmitate ester is most effective in increasing the affinity of the cells for the upper phase, followed by oleate, linolate, linolenate, and deoxycholate esters. The partition behaviour of erythrocytes from various species differs considerably. Two groups can be distinguished: one consisting of erythrocytes from dog, guinea pig and rat, the other from human, sheep and rabbit. This division can be correlated to the content of sphingomyelin and phosphatidyl choline in the erythrocyte membranes. 相似文献
23.
René K. Juhler Eva Andreasson Shi-Gui Yu Per-Åke Albertsson 《Photosynthesis research》1993,35(2):171-178
Thylakoid membranes from spinach were fragmented mechanically and separated into vesicles originating from grana and stroma-exposed lamellae (Andreasson et al. (1988) Biochim Biophys Acta 936: 339–350). The grana vesicles were further fragmented and separated into smaller vesicles originating from different parts of the grana (Svensson and Albertsson (1989) Photosynth Res 20: 249–259). All vesicles so obtained were analyzed with respect to chlorophyll and carotenoid composition by reverse phase HPLC. For all fractions the following relations (mole/mole) were found: 1 carotenoid per 4 chlorophyll (a+b), 2 lutein per 5 chlorophyll b and 5 violaxanthin per 100 chlorophyll (a + b). The contents of lutein and neoxanthin were each linearly related to chlorophyll b and -carotene was linearly related to chlorophyll a. 相似文献
24.
Jan Holgersson Per-Åke Jovall Bo E. Samuelsson Michael E. Breimer 《Glycoconjugate journal》1991,8(5):424-433
Blood group type glycosphingolipids present in kidneys of blood group A and B human individuals have been isolated and structurally characterized by mass spectrometry, proton NMR spectroscopy, degradation studies and by their reactivity with various monoclonal antibodies andEscherichia coli bacteria. The two major complex glycolipids present in the blood group A and B kidneys were globopentaosylceramide (IV3Gal-Gb4Cer) and the X pentaglycosylceramide (III3Fuc-nLc4Cer). The major blood group A glycolipid in the blood group A kidneys was based on the type 4 chain (globo-series). There were also small amounts of the type 2 chain and trace amounts of the type 1 and type 3 chain based A glycolipids. In addition, the blood group H type 4 chain structure was present together with Lea and Leb compounds. In the blood group B kidneys, the major B glycolipids were monofucosylated hexa- and octaglycosylceramides, where the former were based on the type 2 carbohydrate chain. The blood group B type 4 chain heptaglycosylceramide was found to be a minor component making up only about 1% of the total blood group B structures.
Abbreviations: for blood group glycolipid antigens the short hand designation stands for blood group—number of sugar residues—type of carbohydrate chain. Thus A-7-4 means a type 4 chain blood group A heptaglycosylceramide. The sugar types are abbreviated for mass spectrometry to Hex for hexose, HexNAc forN-acetylhexosamine and dHex for deoxyhexose. 相似文献
25.
Plants ofAlnus incana (L.) Moench in symbiosis with a local source ofFrankia were exposed to prolonged darkness under controlled climate conditions.Frankia vesicle clusters were prepared from the root nodules, and the condition ofFrankia was measured as respiratory capacity by supplying the preparation with saturating amounts of four different substrates. During darkness, nitrogenase (EC 1.7.99.2) activity decreased in intact plants and in the vesicle-cluster preparations. The respiratory capacity ofFrankia also decreased. After 4 d in darkness most respiration was lost, though all nitrogenase activity was already lost after 3 d. When the dark treatment was ended after 2 d and normal light/dark conditions restored, nitrogenase activity immediately started to recover. The respiratory capacity continued to decrease and no recovery was observed until the third day after the end of the dark treatment. Whole-plant nitrogenase activity slowly increased at a rate similar to the rate of increase observed in untreated plants. Transmission electron micrographs of the root nodules showed that the cytoplasm of infected host cells and the cells ofFrankia were structurally degraded in response to dark treatment, while young vesicles were frequent during recovery. Growth and differentiation ofFrankia cells were apparently important for recovery of the enzyme activities studied. 相似文献
26.
The isoelectric points of the membranes surrounding three classes of spinach chloroplasts have been determined by partition at different pH values in aqueous two-phase systems where the electrical potential differences at the interface are opposite (cross-partition). Class I chloroplasts, intact chloroplasts, have an isoelectric point at pH 3.8–4.1 and class II chloroplasts, broken chloroplasts or intact thylakoid membranes, have an isoelectric point at pH 4.7–4.9. The third class of particles, class III ‘chloroplasts’, that contain one or more chloroplasts, mitochondria, peroxisomes and some cytoplasm all surrounded by a membrane, probably the plasma membrane, have an isoelectric point at pH 3.4–4.0. The partition technique used presumably yields the isoelectric point of the surface of the membranes exposed to the phase system by the three classes of chloroplasts, i.e., the outer envelope membrane, the thylakoid membrane and the plasma membrane, respectively. The isoelectric points obtained with this technique are suggested to reflect protein to charged-lipid differences in the composition of the membranes. 相似文献
27.
Karin Lindström Per-Åke Jovall Sohbat Ghardashkani Bo E. Samuelsson Michael E. Breimer 《Glycoconjugate journal》1996,13(2):307-313
Total neutral glycolipid fractions were isolated from kidney and ureter tissue obtained at autopsy of an individual of the rare blood group A1 Le(a–b+) p. The amount of glycolipids isolated were 3.7 and 2.5 mg g–1 dry tissue weight for the kidney and ureter tissue, which is in the range of reference blood group P kidneys. Part of the kidney glycolipid fraction was subfractionated by HPLC. Glycolipid compounds were structurally characterized by thin-layer chromatography (chemical detection and immunostaining with monoclonal antibodies), proton NMR spectroscopy and mass spectrometry. Globotriaosyl- and globotetraosyl-ceramides, which are the major compounds in kidneys of P individuals, were absent in the p kidney, and a comparatively increased amount of monoglycosyland lactosylceramides was found. A shift to longer fatty acyl chains in the ceramide part of lactosylceramides was noted. Elongated globoseries compounds with five to seven sugar residues, including the blood group A type 4 chain structure, were lacking. A slight increase in neolactotetraosyl- and blood group X pentaglycosyl-ceramides was noticed. The study confirms an enzymatic block in the conversion of lactosylceramide to elongated globoseries compounds in the kidney tissue similar to that of erythrocytes of p individuals.Abbreviations: for blood group glycolipid antigens the short hand designation stands for: blood group — number of sugar residues — type of carbohydrate chain. Thus A-7-4 means a blood group A heptaglycoconjugate on a type 4 chain. The sugar types are abbreviated for mass spectrometry to Hex for hexose, HexNAc forN-acetylhexosamine and dHex for deoxyhexose. HPLC, high-performance liquid chromatography; HPTLC, high performance thin layer chromatography; EI, electron impact ionisation; LSI, liquid secondary ion; MS, mass spectrometry; NMR, nuclear magnetic resonance. 相似文献
28.
Per-Åke Albertsson 《Photosynthesis research》1995,46(1-2):141-149
Recent work on the domain organization of the thylakoid is reviewed and a model for the thylakoid of higher plants is presented. According to this model the thylakoid membrane is divided into three main domains: the stroma lamellae, the grana margins and the grana core (partitions). These have different biochemical compositions and have specialized functions. Linear electron transport occurs in the grana while cyclic electron transport is restricted to the stroma lamellae. This model is based on the following results and considerations. (1) There is no good candidate for a long-range mobile redox carrier between PS II in the grana and PS I in the stroma lamellae. The lateral diffusion of plastoquinone and plastocyanin is severely restricted by macromolecular crowding in the membrane and the lumen respectively. (2) There is an excess of 14±18% chlorophyll associated with PS I over that of PS II. This excess is assumed to be localized in the stroma lamellae where PS I drives cyclic electron transport. (3) For several plant species, the stroma lamellae account for 20±3% of the thylakoid membrane and the grana (including the appressed regions, margins and end membranes) for the remaining 80%. The amount of stroma lamellae (20%) corresponds to the excess (14–18%) of chlorophyll associated with PS I. (4) The model predicts a quantum requirement of about 10 quanta per oxygen molecule evolved, which is in good agreement with experimentally observed values. (5) There are at least two pools of each of the following components: PS I, PS II, cytochrome bf complex, plastocyanin, ATP synthase and plastoquinone. One pool is in the grana and the other in the stroma compartments. So far, it has been demonstrated that the PS I, PS II and cytochrome bf complexes each differ in their respective pools.Abbreviations PS I and PS II
Photosystem I and II
- P 700
reaction center of PS I
- LHC II
light-harvesting complex II 相似文献
29.
Feifan Yu Lindvi Gudmundsdotter Anastassja Akal Elin Gunneriusson Fredrik Frejd Per-?ke Nygren 《MABS-AUSTIN》2014,6(6):1598-1607
In inflammatory disease conditions, the regulation of the cytokine system is impaired, leading to tissue damages. Here, we used protein engineering to develop biologicals suitable for blocking a combination of inflammation driving cytokines by a single construct. From a set of interleukin (IL)-6-binding affibody molecules selected by phage display, five variants with a capability of blocking the interaction between complexes of soluble IL-6 receptor α (sIL-6Rα) and IL-6 and the co-receptor gp130 were identified. In cell assays designed to analyze any blocking capacity of the classical or the alternative (trans) signaling IL-6 pathways, one variant, ZIL-6_13 with an affinity (KD) for IL-6 of ∼500 pM, showed the best performance. To construct fusion proteins (“AffiMabs”) with dual cytokine specificities, ZIL-6_13 was fused to either the N- or C-terminus of both the heavy and light chains of the anti-tumor necrosis factor (TNF) monoclonal antibody adalimumab (Humira®). One AffiMab construct with ZIL-6_13 positioned at the N-terminus of the heavy chain, denoted ZIL-6_13-HCAda, was determined to be the most optimal, and it was subsequently evaluated in an acute Serum Amyloid A (SAA) model in mice. Administration of the AffiMab or adalimumab prior to challenge with a mix of IL-6 and TNF reduced the levels of serum SAA in a dose-dependent manner. Interestingly, the highest dose (70 mg/kg body weight) of adalimumab only resulted in a 50% reduction of SAA-levels, whereas the corresponding dose of the ZIL-6_13-HCAda AffiMab with combined IL-6/TNF specificity, resulted in SAA levels below the detection limit. 相似文献
30.