Proteinglycosylierung,konserviert von der Bäckerhefe bis zum Menschen: Ein Modellorganismus hilft bei der Aufklärung menschlicher Erbkrankheiten

Proteinmodifikationen durch Saccharide sind in großer Zahl bekannt. Der vorliegende Aufsatz konzentriert sich auf zwei Typen von Modifikationen, die Protein‐N‐Glycosylierung und die Protein‐O‐Mannosylierung, die mit wenigen Ausnahmen von Hefe bis Mensch im Laufe der Evolution konserviert geblieben sind. Sie sind dadurch gekennzeichnet, dass die Glycosylierungsprozesse im endoplasmatischen Reticulum der Zellen beginnen und im Golgi‐Apparat fortgesetzt werden und dass die Anfangsschritte über dolicholaktivierte Vorstufen verlaufen. In der gentechnisch einfach handhabbaren Bäckerhefe Saccharomyces cerevisiae sind die beiden Prozesse molekularbiologisch am besten untersucht worden. Dies ist der Hauptgrund dafür, dass zahlreiche genetisch bedingte, schwerwiegende Entwicklungsstörungen bei Kindern, wie das CDG (Congenital Disorder of Glycosylation) und die kongenitalen Muskeldystrophien mit neuronalen Migrationsdefekten, mithilfe der Hefe aufgeklärt werden konnten.     

A rheological investigation of the self-assembly and adsorption behavior of a surfactant salt

The properties of a surfactant salt obtained by neutralizing oleic acid with an ethoxylated stearylamine were determined in blends of water and propylene glycol. The adsorption of this surfactant salt onto the surface of a commercial TiO(2) dispersed in blends of water and propylene glycol was studied using a rheometer. At low propylene glycol content the dispersions exhibited Newtonian behavior, but became shear-thinning fluids with high viscosity at propylene glycol contents above a critical concentration. The observed behavior is consistent with a model involving a surfactant bilayer below the critical point, moving to a monolayer above the critical point. The high viscosity above the critical point is generated by reversible flocculation via hydrophobic forces. The viscosity of the dispersion flocculated by the hydrophobic forces was found to be much higher than that caused by flocculation via van der Waals forces in the absence of surfactant. Changing both the total concentration of the surfactant in the dispersion and the dispersion temperature resulted in a reversible transition between the bilayer and the monolayer. Although the surfactant was always above its critical micelle concentration (CMC) the amount on the particle surface varied appreciably with both propylene glycol and surfactant concentration.     

Preparation of samples for high-performance liquid chromatography of inositol phosphates.

A simple method is described for the removal of extraneous material from tissue extracts prior to anion-exchange high-performance liquid chromatography of inositol phosphates. Samples are prepared by extraction with trichloroacetic acid or perchloric acid followed by removal of the excess acid. The extracts are then passed through small Dowex-50 cation-exchange columns and eluted with water. Dowex-50 pretreatment removes most of the ultraviolet absorbing material and cations from the samples but does not alter the content of inositol phosphates. This treatment results in improved reliability of chromatography, especially with respect to weakly retained molecules such as adenosine 5'-phosphate and the isomers of inositol monophosphate. In addition, sample pretreatment improves the useful lifetime of the analytical anion-exchange columns.     

A holographic interferometer and fringe analyzer, and their use for the study of supersonic flow

In previous papers the author has discussed the uses of interterometry and holography in aerodynamics, and the design of interferometers using laser sources. The present paper gives a practical example of an application of these techniques to a particular wind tunnel and a particular aerodynamic project.

The nature of the wind tunnel and the type of flow leads naturally to the use of holography with non-diffuse light, and to a particular interferometer design, an aperture-expanding interferometer in which the light is reflected back through the tunnel. It leads also to the use of a sensitivity doubling technique in the analyzer.

The optical and engineering design of the interferometer, analyzer, and of automatic systems for model rotation and camera operation are described. Some results are presented which show that the practical problems have been overcome and that good accuracy is attainable.     

The effect of fermentation (retting) time and harvest time on kudzu (Pueraria lobata) fiber strength

Applied Biochemistry and Biotechnology - The noncommercial kudzu plant has been growing wild in the southern United States since the 1930s. In this article, the kudzu fibrous vine is investigated...     

Calculation in K space of integrals arising in the theory of Van Der Waals forces

Sources of occasional convergence problems in our recently proposed algorithm for orthonormality constrained orbital optimization in SCF calculation, as well as in the partly equivalent orthogonal gradient method, are traced and remedial measures are suggested. A simple scaling technique for accelerating convergence in the related orthogonal gradient method is tested.     

Specific heats of aqueous solutions of NaCl,NaBr, and KCl: Comparisons with related thermal properties

Earlier unpublished measurements of the specific heat capacities of aqueous NaCl, KCl, and NaBr solutions from 5 to 85°C and from 0.05m to saturation are presented. A twin calorimeter was used. A precision of nearly 1 part in 10⁴ in the specific heat capacity is claimed. The results are compared with literature values (summaries or original data) for heat capacity, heat of dilution, and activity coefficient of these salts in solution by means of a polynomial in half-integer powers of molality and temperature. It is found that our values agree well with the more recent literature values of the heat capacities. Small systematic inconsistencies between the various types of data were found.The experimental results presented here are taken from the postdoctoral work of Dr. F. W. Lamb, 1946–47, and from the master's thesis of Dr. J. E. Tanner, Indiana University (1954), obtainable from University Microfilms, Inc., Ann Arbor, Michigan, order number M-763.     

Kinetics of donor–acceptor complex polymerization. IV. Limiting yield in the butadiene–acrylonitrile copolymerization

An analysis of the kinetic equation proposed for donor–acceptor systems indicated that the polymer yield at a given time should attain limiting value with increase in rate of initiation. It was essential that the equilibria not be shifted by temperature variation, and the change in rate of initiation was achieved by controlled current passage through the solution. A definite plateau in the yield of polymer was obtained. This was shown not to be due to diffusion control of the rate of initiation.     

1,6:9,14-bismethano[16]annulene - a new bridged [4n]annulene

The molecular structure and dynamic behaviour of the bridged [4n] annulene 1,6:9,14-bismethano-[16]annulene is unravelled by NMR and X-ray investigations, combined with force field calculations.     

Synthesis of C59Hx and C58Hx fullerenes stabilized by hydrogen

Prolonged hydrogenation of C(60) molecules by reaction with H(2) at elevated temperature and pressure results in fragmentation and collapse of the fullerene cage structure. However, fragments can be preserved by immediate termination of dangling bonds by hydrogen. Here we demonstrate that not only fullerene fragments but also hydrogenated fragmented fullerenes (e.g., C(58)H(40) and C(59)H(40)) can be synthesized in bulk amount by high-temperature hydrogenation of C(60). We confirm successful synthesis of these species by matrix-assisted laser desorption ionization time-of-flight mass spectrometry and complete speciation of the resultant complex fullerene mixtures by high-resolution field desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry.