Characterization of the isolated calcium-binding vesicles from the green alga Mougeotia scalaris,and their relevance to chloroplast movement

The calcium-binding vesicles from the green alga Mougeotia scalaris were isolated and characterized after staining in vivo by neutral red or rhodamine B. They were found to possess, a protonated group with a pK_a-9.9, typifying phenolic hydroxyl groups; upon titration, both, phenolic compound(s) and vital dye were concomitantly released from the vesicular matrix. A shift in peak absorbance from 450 nm to 540 nm of the vitally stained vesicles indicated that the neutral form of neutral red was bound to the vesicular, matrix as an intermediate form, stabilized via intermolecular hydrogen bonds to the phenolic compound(s). Up to 8.5.10⁹ dye molecules were calculated to be adsorbed to a mean-size vesicle. Analysis of Langmuir adsorption isotherms, indicated that there were two binding sites each for both neutral red and rhodamine B. The isolated vesicles were devoid of calcium, probably because vesicular calcium, bound to the vesicle matrix, was displaced upon dye binding. Dye adsorption to the vesicles in vivo results in substantial inhibition of the reorientational movement of the Mougeotia chloroplast and is explained by dye-mediated disorder of the cellular calcium homoeostasis.Abbreviations NR neutral red - RB rhodamine B - SDS sodium dodecyl sulfate This paper is part of the Ph.D. thesis of F. Grolig at Justus-Liebig-Universität Giessen, FRG     

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Preparative and analytical separation of the zopiclone enantiomers and determination of their affinity to the benzodiazepine receptor binding site

We report the preparative separation of rac-zopiclone using malic acid as the resolving agent. Furthermore, two different methods for the analytical determination of zopiclone enantiomers by HPLC on chiral stationary phases are described. The benzodiazepine receptor binding of the isolated enantiomers was investigated. Half-maximal inhibitory concentrations of (+)- and (?)-zopiclone were 21 or 1,130 nmol/liter, respectively, indicating a more than 50 times higher affinity of the (+)-enantiomer toward the receptor. © 1993 Wiley-Liss, Inc.     

Die Lichtreaktionen der Hydren

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A membrane-associated creatine kinase (EC 2.7.3.2) identified as an acidic species of the non-receptor,peripheral v-proteins in Torpedo acetylcholine receptor membranes

Human liver mRNA isolated from subjects phenotyped as homozygous PiMM or PiZZ α₁-antitrypsin, was translated in a reticulocyte cell-free system, and α₁-antitrypsin identified by immunoprecipitation. In the presence of dog pancreas membranes the translated α₁-antitrypsin appeared as a larger product. Treatment with endo-β-N-glucosaminidase yielded a protein smaller than the reticulocyte translated product, presumably due to removal of the N-terminal signal sequence by membranes and sugar residues by endo-β-N-glucosaminidase. Quantitation of α₁-antitrypsin translated from PiMM and PiZZ livers suggests that both mRNA species were present at the same cellular concentration, and that processing to the core glycosylation stage proceeded at identical rates.     

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