Polarographie schwefelhaltiger Proteine

Zusammenfassung An kristallisierten Enzymen des biologischen Stoffwechsel wird gezeigt, daß bei der Polarographie nur die schwefelhaltigen Proteine katalytische Wasserstoffwellen geben. Von den in der Literatur beschriebenen Doppelstufen der Proteine besitzt nur die im negativeren Potentialbereich liegende Welle die eigentliche katalytische Funktion. Die erste Vorwelle von Proteinen verschwindet, wenn die polarographische Messung bei 0° C durchgeführt wird.In Proteinen sind nur Disulfidgruppen katalytisch wirksam. Sogenannte reine Sulfhydryl-Enzyme haben keinen katalytischen Effekt. Typische SH-Enzyme können jedoch polarographisch als p-Chloromercuribenzoatkomplexe gemessen werden.Durch Harnstoffzusatz bei der polarographischen Messung von Proteinen gelingt es, zwischen maskierten und freien Sulfhydryl- oder Disulfidgruppen an Enzymen zu definieren.Auszug aus der Dissertationsschrift H. Katzlmeier, Technische Hochschule München (1959).     

Aqueous Solution Chemistry of the Mo(3)PdS(4) Cube: Substitution Reactions and the Double to Single Cube Interconversion Induced by CO, Two Phosphines, Cl(-), Br(-), and NCS(-)

The kinetics of conversion of an edge-linked double cube, in this case [{Mo(3)PdS(4)(H(2)O)(9)}(2)](8+), to the corresponding single cube [Mo(3)(PdX)S(4)(H(2)O)(9)](4+), has been studied for the first time. Reaction is induced by six reagents X = CO, two water-soluble phosphines, Cl(-), Br(-), and NCS(-), which complex at the tetrahedral Pd. The first stage of reaction is fast and is accompanied by color changes, e.g. purple to dark blue in the case of Cl(-), assigned as double to single cube conversion. With X = CO and the two phosphines, when absorbance changes are intense enough for stopped-flow monitoring with reactants at Pd-SCN. On removal of e.g. Cl(-) by chromatography or addition of Ag(+), the double cube re-forms.     

Effect of non-planarity on the spin distribution in the radical anions containing the stilbene or the azobenzene π-system: An ESR and ENDOR Study

The radical anions of 5H-dibenzo[a,d]cycloheptene ( 9 ), 5 H-dibenzo[c,f][1,2]diazepine ( 10 ), 5,6-dihydrodibenzo[a,e]cyclooctene ( 11 ), 5,6-dihydrodibenzo[c,g][1,2]diazocine ( 12 ), and (E)-2,2,5,5-tetramethyl-3,4-diphenylhex-3-ene ( 13 ) were characterized by ESR and ENDOR spectroscopy. Their hyperfine data were compared with those previously reported for radical anions also containing the stilbene or the azobenzene π-system. Whereas the π-spin distribution in the radical anions of the stilbene series is only moderately sensitive to deviations of the π-system from planarity, the radical anions of the azobenzene series respond to steric strain by shifting the π-spin population from the benzene rings to the azo group. This finding is impressively demonstrated by the similar hyperfine data for 9 ^{· ?} and 11 ^{· ?} which contrast with the strongly highly hindered 13 ^{· ?}. A. plausible interpretation is readily provided by the electron affinities of the constituent π-moieties in stilbene and azobenzene. While those of benzene and ethene are both comparatively low, the azo group has a considerably higher electron affinity.     

The gastroprotective effect of oxycellulose pellets on gastric ulcers

Oxycellulose belongs to the wide range of pharmaceutically and medically used cellulose derivatives unique in its properties of biodegradability, non-toxicity, antioxidative activity, haemostasis supporting, tissue healing improvement, etc. Glycyrrhizin (Gly) represents the most prominent licorice triterpenoid glycoside, which is responsible for its pharmacological activity, and is closely linked to increasing levels of gastroprotective prostaglandins. In order to study the anti-ulcer activity of oxycellulose sodium and Gly, pellets containing only oxycellulose, or in combination with glycyrrhizin, were prepared using an extrusion/spheronization method. The physical properties and in vitro release rate of the prepared pellets were tested. Based on the obtained results, one sample prepared from oxycellulose only, and one containing glycyrrhizin were chosen for in vivo testing. The healing effect of the prepared pellet formulations was evaluated in the acetic acid induced gastric ulcers in rats. The improvement in gastric ulcer healing was documented for myeloperoxidase activity, alkaline phosphatase activity and gastric wall mucin levels using the Alcian blue binding capacity. The tested pellets significantly reduced myeloperoxidase and alkaline phosphatase activity, and increased gastric wall mucus levels compared to the non-treated group. The in vivo tests showed that oral administration of the prepared pellets accelerated the healing of gastric ulcers in rats.     

Liquid chromatographic enrichment ofN-acetylmethionine from casein hydrolysates for stable-isotope-ratio analysis of sulfur

Summary A chromatographic method has been developed for enrichment of methionine-bound sulfur in casein, for stable-isotope analysis. Casein is precipitated from milk samples and cleaved by acid hydrolysis in 6m hydrochloric acid at 95 °C. The amino acids released are converted into theirN-acetyl derivatives by addition of acetic acid anhydride. After lyophilization,N-acetylmethionine is separated from the accompanying components on octadecylsilica by use of a gradient prepared from 0.02m formic acid and methanol. The fractions containingN-acetylmethionine are pooled and freeze dried. Procedures for hydrolysis and derivatization were optimized to furnish the highest yields. The influence of the abundance ratio on the chromatographic separation is shown and discussed. From 1.0 g casein 16.5 mgN-acetylmethionine were isolated.     

Spectrally selective organic photodiodes

We report on the fabrication of spectrally selective organic photodiodes (OPDs) and present a green sensitive OPD, whose spectral response peaks in the green region between 470 nm and 560 nm, as well as a red sensitive OPD whose spectral response peaks in the red region between 610 nm to 720 nm. We show that the spectral sensitivity of OPDs can be tuned by either choosing organic semiconductors with the appropriate photoresponse or by utilizing adequate device architectures with integrated optical filters. The results demonstrate the great flexibility of organic semiconductor materials. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Studies on the biodegradation of fosfomycin: synthesis of 13C-labeled intermediates, feeding experiments with Rhizobium huakuii PMY1, and isolation of labeled amino acids from cell mass by HPLC

Racemic (1R*,2R*)‐1,2‐dihydroxy‐[1‐¹³C₁]propylphosphonic acid and 1‐hydroxy‐[1‐¹³C₁]acetone were synthesized and fed to R. huakuii PMY1. Alanine and a mixture of valine and methionine were isolated as their N‐acetyl derivatives from the cell hydrolysate by reversed‐phase HPLC and analyzed by NMR spectroscopy. It was found that the carbon atoms of the respective carboxyl groups were highly ¹³C‐labeled (up to 65 %). Hydroxyacetone is therefore considered an obligatory intermediate of the biodegradation of fosfomycin by R. huakuii PMY1.     

Bestimmung von Corticosteroiden im Blut durch Doppelmarkierung und Messung von 14C und 3H in der Gasphase

Ohne ZusammenfassungAuszug aus der Dissertation Reinhard Ködding, Technische Hochschule München 1961.     

Enzymatische Bestimmung von Gallensäuren in Körperflüssigkeiten und Geweben

A method for the quantitative determination of bile acids in serum, bile and liver is described. Tetran-heptylammonium salts of the bile acids are extracted from aqueous solutions by means of ethyl acetate. For the enzymatic analysis with 3 α-hydroxysteroid-NAD-oxidoreductase (E.C. 1.1.1.50) the bile acids are isolated from their tetra-n-heptylammonium compounds by cationic exchange (Dowex 50 WX 2).