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Zur quantitativen Plasmaproteinbestimmung sind die Immunnephelometrie und die Immunturbidimetrie häufig eingesetzte Bestimmungstechniken. Aufgrund der kürzeren Analysenzeit bei vergleichbarer oder besserer Präzision und Empfindlichkeit haben diese Techniken die radiale Immundiffusion in vielen Laboratorien ersetzt.
Die mechanisierte Plasmaproteinbestimmung erfolgt als Antigen-Antikörper-Reaktion entweder mit Proteinanalyzern oder mit klinisch-chemischen Analysensystemen, an denen normalerweise Enzyme und Substrate bestimmt werden.
Zwischen den verschiedenen Plasmaproteinen im Serum besteht ein bis zu 10.OOOfacher Konzentrationsunterschied und die biologische Varianz des einzelnen Plasmaproteins ist breit Damit die Plasmaproteine mit hoher analytischer Sensitivität über einen weiten Konzentrationsbereich, mit guter Präzision und der erforderlichen Richtigkeit mechanisiert bestimmt werden können, ist eine gute Adaption des Immunreagenzes auf das mechanisierte Analysensystem erforderlich. Diese Übersicht soll dazu Grundlagen vermitteln.
A first model of the three-dimensional structure of the photosynthetic reaction center of the mutant T1 (SerL 223 → Ala, ArgL 217 → His) from Rhodopseudomonas viridis, resistant toward the triazine herbicide terbutryn (2-methylthio-4-ethylamino-6-f-butylamino-5-triazine), has been developed from X-ray data measured to a resolution of 2.5 Å. The secondary quinone, QB, which in T1 binds better than in the wild type, is present in the crystals. Both substituted residues are clearly visible in the difference fourier map. The replacement of these two residues in the QB site causes only minor changes in the overall structure of the protein.
The anion transport protein of the human erythrocyte membrane, band 3, was solubilized and purified in solutions of the non-ionic detergent nonaethylene glycol lauryl ether and then reconstituted in spherical egg phosphatidylcholine bilayers as described earlier (U. Scheuring, K. Kollewe, W. Haase, and D. Schubert, J. Membrane Biol. 90, 123-135 (1986)). The resulting paucilamellar proteoliposom es of average diameter 70 nm were transformed into smaller vesicles by French press treatment and fractionated according to size by gel filtration. The smallest protein-containing liposomes obtained had diameters around 32 nm; still smaller vesicles were free of protein. All proteoliposome samples studied showed a rapid sulfate efflux which was sensitive to specific inhibitors of band 3-mediated anion exchange. In addition, the orientation of the transport protein in the vesicle membranes was found to be “right-side-out” in all samples. This suggests that the orientation of the protein in the vesicle membranes is dictated by the shape of the protein’s intramembrane domain and that this domain has the form of a truncated cone or pyramid.
Four atrazine-resistant mutants from the purple bacterium Rhodopseudom onas viridis were isolated. Sequence analysis revealed three different mutant strains carrying mutations in the herbicide-binding pocket: i) M AV 2: L 212-Glu → Lys, ii) M AV 3: L216-Phe → Ser and iii) MAV 4 = MAV 5: L217-Arg → His, L220-Val → Leu. Except M AV 3 all Rps. viridis mutants are different from those selected by their resistance towards the closely related triazine terbutryn.
Mutants of Anacystis R2 with different amino acid exchanges in positions 255 and/or 264 in copy I of the psbA gene, leading to different tolerances to DCMU-type herbicides, are com- pared with the respective wild type concerning pigmentation and incorporation of 35S into the D1 protein upon growth in the presence of [35S]methionine. All mutants have shade-type appearance compared to the wild type, although to different extents depending on site and mode of the amino acid exchange in the D1 protein. Except for 3 mutants, there is no correlation between shade-type appearance on one hand and resistance towards a certain inhibitor on the other hand.
Not only the molar ratio of phycocyanin (PC) to chlorophyll (Chi) is higher in all mutants compared to the respective wild type, but also the rate of synthesis of the D1 protein. On the background of different levels of total 35S incorporation within 18 min, D1 synthesis can be related to shade adaptation. Degradation of the D1 protein remains to be thoroughly studied in this context.
No reproducible differences in whole chain electron transport were observed between mutants and wild type.
Lactate dehydrogenase from pig heart is inactivated by the NAD+ -analog P1-N6-(4-azidophenylethyl)adenosine-P2-[4-(3-azidopyridinio)butyl]diphosphate (6) upon irradiation with UV light of wavelengths in the range from 300 to 380 nm. The decrease in enzyme activity can be prevented by the addition of NAD+ and oxalate. The modified enzyme shows a reduced binding capacity for its coenzyme as compared to native lactate dehydrogenase. The amount of incorporated coenzyme is deduced from the ribose content of inactivated enzyme. Tryptic digestion of the modified protein and separation of the peptides by HPLC yields 5 ribose-containing fractions. One of them, fraction 6 6 , is split by treatment with nucleotide pyrophosphatase into two subfractions, 63 and 58. Only subfraction 63 contains ribose. Whereas peptide 58 shows a UV absorption spectrum similar to that of 4-(3-aminopyridinio)-butyl phosphate (3). Amino acid analyses of the peptides indicate that the inactivator forms covalent bonds with different parts of the protein: Peptide 63 is characterized by a great portion of hydrophobic amino acids whereas peptide 58 shows a high degree of hydrophilicity.
In the course of the odontogenesis of bovine incisors several clearly distinguishable phosphohydrolase activities are observed in the pulp and in dental hard tissues. Using various substrates and inhibitors, unspecific alkaline phosphatase, two isoenzymes of acid phosphatase, Ca2+-activated ATPase and inorganic pyrophosphatase are characterized. The enzymatic activity of alkaline phosphatase in pulp and hard tissues is significantly high at the beginning of dentine and enamel mineralization. The specific activity of this enzyme decreases quite fast with the beginning of root formation, then more slowly, until it reaches a constant final value. Histochemical studies show that during mineralization the maximum of alkaline phosphatase activity is in the subodontoblasts. Lower enzyme concentrations are found in the stratum intermedium and in the outer enamel epithelium during that process.
The specific activities of ATPase, acid phosphatases and pyrophosphatase show little temporal variation during tooth development, but they also appear in a characteristic spatial pattern in the dental tissues.
The radical anion of dimesityltetraketone (ERed, I = -0.40 V) is easily generated in THF by potassium mirror/[2.2.2]-cryptand reduction. Its contact ion pairs with Na⊕, Cs⊕ and Ba⊕⊕ counter cations, prepared in THF solution by single electron transfer from the respective metals, are characterized by their ESR/ENDOR spectra, which exhibit temperature-dependent metal couplings of aNa⊕ = 0.061 mT (190 K), aCs⊕ = 0.021 mT (190 K), and aBa⊕⊕ = 0.145 mT (295 K).
The absolute configurations of the diastereomeric 10-hydroxyaloins, which may be regarded as parent structures for other naturally occurring oxanthrone-C-glucosyls, have been established as 10R, 16 R (A) and 10 S, 16 R (B) by an X-ray structure analysis of the A-octaacetyl derivative (C 16 is the anomeric glucosyl carbon atom). The determination was confirmed by CD spectroscopic comparison with the structural analogues aloins A and B, which should prove useful for making future configurational assignments within this class of compounds. A conformational analysis by the use of a molecular modeling method based on force-field calculations reveals the presence of an extra- and an intra-form, the extra-form of which is energetically preferred.