A New X-Ray Method for the Determination of the Quaternary Structure of Protein Complexes

The determination of the spatial arrangement of subunits in protein complexes is possible by an application of a new method. After appropriate labelling of the subunits with heavy atoms the distances between the subunits can be found from X-ray experiments. Theoretical and experimental considerations allow us to deduce these distances and to find the relative positions of the subunits within the protein complex.     

Lexical decision as an indirect test of memory: Repetition priming and list-wide priming as a function of type of encoding.

Two experiments examined priming in the lexical decision task, an indirect test of memory. Experiment 1 manipulated type of processing during study of unrelated word pairs. Recognition of individual words benefited more from semantic than from nonsemantic processing. Repetition priming in lexical decision depended on the context in which the target appeared. Targets preceded at test by unstudied primes showed greater repetition priming if processed nonsemantically during study; targets preceded at test by studied primes were not affected by type of processing at study. Interestingly, studied targets were facilitated more by studied than by unstudied primes regardless of whether the prime came from the same pair as the target. This list-wide episodic priming occurred under all four processing conditions in Experiment 1 (consonant counting, rote rehearsal, pleasantness rating, and sentence generation) with a 250-ms stimulus onset asynchrony. Experiment 2 showed that this list-wide episodic priming disappeared by 1,000 ms, suggesting that it had resulted from relatively transient activation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis and crystal structure of the inter-alkali-metal chloride RbLiCl2

The crystal structure of RbLiCl₂ [a= 1441.3(3), b= 412.57(8), c= 720.9(1) pm, Guinier-Simon data, orthorhombic, Ccmm, No. 63, Z= 4] was determined and refined from single crystal data, R= 0.074, R_W= 0.062. The coordination polyhedron of Rb⁺ is a bicapped trigonal prism, Li⁺ is tetrahedrally coordinated. [LiCl₄] tetrahedra are connected via common corners to undulated layers $\text{∞}\text{2}\text{[}\text{LiCl}{}^{\mathrm{c}}{}_{\mathrm{<mtext>4</mtext><mtext>2</mtext>}}\text{]}{}^{\mathrm{?}}$ parallel to (100). The structure is closely related to that of SrZnO₂.     

Zur Bestimmung der Wasseraufnahmefähigkeit pulverförmiger Proteinrohstoffe 1. Mitt. Die Kapillarsaugmethode

Die Kapillarsaugmethode ermöglicht eine einfache und schnelle Bestimmung der Wasseraufnahmefähigkeit pulverförmiger Proteinrohstoffe. In Untersuchungen an 10 verschiedenen Proteinrohstoffen wird ge-zeigt. daß sich mit zunehmender Einwaage (Schichtdicke) die in g Wasser/g Pulver ausgedrückte Wasseraufnahme leicht erhöht. Bei Einwaagen zwischen 50 und 200 mg ist die Abhängigkeit jedoch so gering, daß sie vernachlässigt werden kann. Mit der Korngröße nimmt die Wasseraufnahme exponentiell zu. Nur bei Korngrößen zwischen 50 und 110 μm Durchmesser kann dies außer acht gelassen werden. Die Art des Proteinrohstoffs, Temperatur, pH-Wert und Ionenmilieu wirken sich unterschiedlich aus. Die Standardabweichung der Methode ist bei Proteinrohstoffen unabhängig von der Größe des Meßwertes und betragt 0,075 g je g Die Bestimmungsgrenze des Verfahrens liegt für eine Einzelbestimmung bei 0,28 und für eine Dreifach-bestimmung bei 0,16 g/g. Die mit der Kapillarsaugmethode verfolgte Wasseraufnahme von Proteinrohstoffen kann nach einer Kinetik nullter (Vorgang mit konstanter Wasseraufnahmerate, z. B. Quellung) oder erster Ordnung (Adsorption) verlaufen, bzw. sie geht in eine gemischte Kinetik über. L. HEINEVFTTER, J. KROLL, B. GASSMANN and K. HOPPE: Determination of the capability of water uptaking by powdery protein raw materials. Part 1. The capillary suction method. The capillary suction method permits simple and rapid determination of the capability of water uptaking by powdery protein raw materials. Investigations with 10 different protein raw materials have demonstrated, that the water uptake expressed in gram water per gram powder is weakly increased, if the amount of sample taken and the layer thickness respectively has been increased. At amounts in the range of 50 to 200 mg however this dependence is insignificantly, so it may be neglected. The water uptake increases exponentially with increasing particle size. Only in case of particle sizes with diameters between 50 and 110 μm this may be ignored. Kind of protein material, temperature, pH value and ion relationships have diverse effects. The Standard deviation of the method related to protein raw materials is independent of the value order measured and amounts 0,075 g/g. The detection limit of the method in case of single determinations is about 0.28 g/g and in case of triple determinations it is 0,16 g/g. The water uptake by protein raw materials followed up with the capillary suction method can be represented by a zero order kinetics (process with constant water uptake rate, i.e. swelling) or by a first order kinetics (water adsorption), otherwise the water uptake rate-may change over to a mixed order kinetics.