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1.
Bodil Kjær Yean-Sung Jung Lian Yu John H. Golbeck Henrik Vibe Scheller 《Photosynthesis research》1994,41(1):105-114
The photosynthetic reaction center complex from the green sulfur bacteriumChlorobium vibrioforme has been isolated under anaerobic conditions. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis reveals polypeptides with apparent molecular masses of 80, 40, 30, 18, 15, and 9 kDa. The 80- and 18-kDa polypeptides are identified as the reaction center polypeptide and the secondary donor cytochromec
551 encoded by thepscA andpscC genes, respectively. N-terminal amino acid sequences identify the 40-kDa polypeptide as the bacteriochlorophylla-protein of the baseplate (the Fenna-Matthews-Olson protein) and the 30-kDa polypeptide as the putative 2[4Fe-4S] protein encoded bypscB. Electron paramagnetic resonance (EPR) analysis shows the presence of an iron-sulfur cluster which is irreversibly photoreduced at 9K. Photoaccumulation at higher temperature shows the presence of an additional photoreduced cluster. The EPR spectra of the two iron-sulfur clusters resemble those of FA and FB of Photosystem I, but also show significantly differentg-values, lineshapes, and temperature and power dependencies. We suggest that the two centers are designated Center I (with calculatedg-values of 2.085, 1.898, 1.841), and Center II (with calculatedg-values of 2.083, 1.941, 1.878). The data suggest that Centers I and II are bound to thepscB polypeptide. 相似文献
2.
Iron-sulfur core extrusions from spinach [( 2Fe-2S]) and Clostridium pasteurianum (2[4Fe-4S]) ferredoxins in aqueous Triton X-100/urea containing excess benzenethiol yield quantitatively [FenSn(SPh)4]2- with n = 2 and n = 4, respectively. The iron-sulfur cluster can be separated from the corresponding apoprotein by rapid passage of the extrusion mixture over a small anaerobic column of Whatman DE-52 anion-exchange cellulose. Essentially quantitative recovery of [FenSn (SPh)4]2- is achieved in the eluate. The apoprotein remaining on the column can be eluted with 0.5 M NaCl. Most of the residual Triton X-100 and benzenethiol can be removed by passage of the apoprotein eluate over a small column of Bio-Beads SM-2, a hydrophobic polystyrene adsorbent. Apoprotein recovery is comparable to that obtained by other chromatographic methods. At least with spinach ferredoxin, the apoprotein prepared in this fashion can be reconstituted. The procedures developed in this work are potentially most applicable to selective removal of [2Fe-2S] and [4Fe-4S] centers from a multicenter enzyme without irreversible denaturation. 相似文献
3.
《Cell》2021,184(22):5670-5685.e23
4.
Laran T. Jensen J. M. Peltier Dennis R. Winge 《Journal of biological inorganic chemistry》1998,3(6):627-631
Mammalian metallothioneins (MT) are known to maximally bind 12 copper ions in two six-Cu(I) ion clusters. Using electrospray
ionization mass spectrometry of MT at pH 4.5, a four-Cu(I) ion cluster was observed intermediate to a fully formed six Cu(I)
in a single domain or a fully formed Cu12MT species. The four-Cu(I) cluster was observed in both MT1 and MT3 isoforms. Addition of increasing amounts of Cu(I) to MT
at pH 4.5 resulted in prominent ions whoses masses were consistent with apo-MT, Cu4MT, Cu6MT, and Cu12MT. The cooperativity of cluster formation was reduced at pH 2.5. Addition of Cu(I) to apo-MT at a reduced pH resulted in
a series of ions consistent with Cu4 to Cu12MT species. However, formation of the tetracopper MT species remained cooperative at low pH, suggesting that this species
is very stable. To determine whether the tetracopper cluster was formed in either the α or β domain, domain peptides of MT3
were used. Addition of Cu(I) to the apo β domain resulted in a peak consistent with the formation of a four-Cu(I) cluster.
This is consistent with reports that Cu(I) ions bind preferentially to the β domain of MTs.
Received: 2 June 1998 / Accepted: 21 August 1998 相似文献
5.
Peter-Leon Hagedoorn Laura van der Weel Wilfred R. Hagen 《Journal of visualized experiments : JoVE》2014,(93)
Electron Paramagnetic Resonance (EPR) monitored redox titrations are a powerful method to determine the midpoint potential of cofactors in proteins and to identify and quantify the cofactors in their detectable redox state.The technique is complementary to direct electrochemistry (voltammetry) approaches, as it does not offer information on electron transfer rates, but does establish the identity and redox state of the cofactors in the protein under study. The technique is widely applicable to any protein containing an electron paramagnetic resonance (EPR) detectable cofactor.A typical titration requires 2 ml protein with a cofactor concentration in the range of 1-100 µM. The protein is titrated with a chemical reductant (sodium dithionite) or oxidant (potassium ferricyanide) in order to poise the sample at a certain potential. A platinum wire and a Ag/AgCl reference electrode are connected to a voltmeter to measure the potential of the protein solution. A set of 13 different redox mediators is used to equilibrate between the redox cofactors of the protein and the electrodes. Samples are drawn at different potentials and the Electron Paramagnetic Resonance spectra, characteristic for the different redox cofactors in the protein, are measured. The plot of the signal intensity versus the sample potential is analyzed using the Nernst equation in order to determine the midpoint potential of the cofactor. 相似文献
6.
P. Huart R. Brasseur E. Goormaghtigh J.M. Ruysschaert 《Biochimica et Biophysica Acta (BBA)/General Subjects》1984,799(2):199-202
We demonstrate here that drugs which inactivate cytochrome c oxidase are able to segregate cardiolipin essential for the enzyme activity, in a separate phase inaccessible for the enzyme. A molecular explanation of the drug-induced aggregation process is proposed. 相似文献
7.
Lokesh Bhattacharyya Martin Haraldsson Nathan Sharon Halina Lis Fred Brewer 《Glycoconjugate journal》1989,6(1):141-150
Erythrina lectins possess similar structural and carbohydrate binding properties. Recently, tri- and tetra-antennary complex type carbohydrates with non-reducing terminal galactose residues have been shown to be precipitated as tri- and tetravalent ligands, respectively, with certainErythrina lectins [Bhattacharyya L, Haraldsson M, Brewer CF (1988) Biochemistry 271034-41]. The present work describes a comparative study of the binding and precipitating activities of fourErythrina lectins,viz. E. corallodendron, E. cristagalli, E. flabelliformis, andE. indica, with multi-antennary complex type carbohydrates and synthetic cluster glycosides. The results show that though their binding affinities are very similar, theErythrina lectins show large differences in their precipitating activities with the carbohydrates. The results also indicate significant dependence of the precipitating activities of the lectins on the core structure of the carbohydrates. These findings provide a new dimension to the structure-activity relationship of the lectins and their interactions with asparagine-linked carbohydrates.Abbreviations EAL, ECorL, ECL, EFL, and EIL
represent the lectins from the seeds ofErythrina arborescens,
-
E. corallodendron, E. cristagalli, E. flabelliformis, andE. indica
respectively
- AFOS
thetri-antennary complex type oligosaccharide from asialofetuin
- AFGP
the tri-antennary glycopeptide from asialofetuin
- MeGal
methyl -d-galactopyranoside
Unless stated otherwise all sugars are in thed-configuration. 相似文献
8.
J Dupont J F Rodes J Berreur-Bonnenfant M C Carre A Tekitek P Berreur 《Biology of the cell / under the auspices of the European Cell Biology Organization》1989,67(2):141-146
Farnesylacetone (C18 H30 0) is a male hormone extracted from the androgenic gland of crab, Carcinus maenas. Appropriate enzymatic assays, as well as spectrophotometric studies, indicate that micromolar concentrations of farnesylacetone interact with the electron transport pathway of rat liver mitochondria. By the use of artificial electron donors and electron acceptors, it is shown that farnesylacetone immediately inhibits the electron transfer within complex I (NADH ubiquinone reductase activity) and complex II (succinate ubiquinone reductase activity). It is proposed that farneylacetone could interact with these two complexes of the respiratory chain at the level of the iron-sulfur centers implicated in the dehydrogenase activities. These observations are compared with the results obtained with terpenic molecules which interact with mitochondrial respiration. 相似文献
9.
10.
本文研究了中国广东汉族健康人群apoAI-CⅢ-AIV基因簇DNA限制性内切酶PstI、SstI和EcoRI片段长度多态性。其中等位基因P_1,P_2,S_1,S_2,R_1和R_2的频率分别为0.98,0.02,0.96,0.04,0.90和0.10。经卡方检验符合Hardy-Weinbery氏遗传平衡,与其他种族比较,本文结果显示中国广东汉族人P_2等位基因频率低于日本人、亚洲印第安人和高加索人,S_2等位基因频率低于日本人、菲律宾人、沙特阿拉伯人和亚洲印第安人,而与高加索人相近,R_2等位基因频率稍高于高加索人。不同种族间apoAI-CⅢ-AIV基因簇DNA多态频率无疑存在差异,这种差异可能是由于遗传漂变和自然选择单独或联合作用所致。对P_1、P_2,S_1、S_2和R_1、R_2构成的单倍型和连锁平衡程度进行了分析,结果显示这些单倍型处于连锁不平衡状态。 相似文献