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Biomedical subjects

U Rothe

Publications and source records attributed to U Rothe.

27 records · Page 2Linked to original sources
PubMed1986

Determination of antibodies to rubella virus with the disperse dye immunoassay (DIA) in comparison with an enzyme-linked immunosorbent assay (ELISA).

A disperse dye immunoassay (DIA) using Fantagen-dye sol particles as label was developed for the measurement of rubella antibodies in human serum specimen. The DIA has a sensitivity comparable to the hemagglutination-inhibition (HI) test, whereas the detection limit for a similar ELISA-system developed in parallel is lower by a factor of about two orders of magnitude. The results of testing 34 random serum specimens with the 3 different methods showed a significant correlation (v = 0.73 for DIA vs. ELISA). Titer rises in 10 paired sera (acute/convalescent) estimated with the DIA- and ELISA-methods were in good agreement with H1-results. Only two of the 10 pairs differed in titer rise by no more than one dilution step.

Antibodies, Viral↗
PubMed1985

[The kinetics of hydrolysis of alanine peptide esters and -p-nitroanilides by thermitase, a thermostable serine protease from Thermoactinomyces vulgaris: secondary specificity, influence of temperature and solute].

The kinetic parameters Km and kcat and the resulting proteolytic coefficients kcat/Km for the hydrolysis of blocked alanine peptide esters (X(Ala)nOMe) and -p-nitroanilides (X(Ala)n-pNA) of variable length (n = 1 to 5 alanine residues) by the cationic, microbial serine protease thermitase are determined in order to delineate the number of subsites involved in catalysis. Thermitase has at least five secondary subsites (S1 to S5) being hydrophobic in S1 to S4. Arrhenius plots for both, esterase and amidase activity were biphasic with a break at 30 degrees C, followed by a downward bend. The influence of dimethylformamide, solute for many substrates, on the thermitase-catalyzed esterolysis of Z(Ala)2OMe was also investigated. In contrast to the kcat values being unaffected by 5 to 30% dimethylformamide, the Km values increased logarithmically with enhancing its concentration.

Alanine↗
PubMed1982

Investigations on the substrate specificity of thermitase, a thermostable serine-protease from Thermoactinomyces vulgaris.

The kinetic parameters Km and kcat and the proteolytic coefficients kcat/Km for the hydrolysis of eighteen Z(benzyloxycarbonyl)-dipeptide methyl esters with variation of the residues in P1 and P2 position catalyzed by thermitase at pH 8 and 55 degrees C are reported. The results indicate that an integral part of both subsites, S1 and S2, are hydrophobic areas and that a mutual interaction between the side chains of P1 and P2 for optimal hydrolyisis does exist. Furthermore, the importance of the P2 for the peptidolytic activity of thermitase was shown using N-acylated oligo-alanine peptides and their p-nitroanilides. In all cases dialanine or alanine p-nitroanilide are the main products.

Endopeptidases↗
PubMed1977

[Isolation, crystallization and partial characterization of a cationic protease from thermoactinomyces vulgaris].

A simple method was developed for the isolation of the cationic endopeptidase from a crude extract prepared from the culture medium of Thermoactinomy ces vulgaris, consisting in chromatography on Sephadex G 75 and subsequent separation on CM-Sephadex in 50 mM Tris/HCl, pH 8, using a NaCl-gradient (0 - 0,2 M). This procedure results in a 4,2 fold increase of the elastolytic activity (substrate: N-acetyl-(L-ala)3methyl ester) of the enzyme. It moves as a single band in SDS-gel electrophoresis and crystallizes as needles up to 0,2 mm in length after standing at 5 degrees C in 50 mM Tris/HCl (pH 8,3).

Cations↗
PubMed1976

[Enzymatic conversion of tetradecanol in heterogenous phase by yeast-alcohol dehydrogenase].

Alcohol dehydrogenase from yeast converts long-chain primary alcohols not only in the dissolved state, but also at the surface of undissolved particles. Tetradecanol beads with a defined surface can be produced and employed as model substrate. The reaction rate was determined by the proton release accomplished in the reaction. The initial reaction rate depends on the enzyme concentration. The relation is nonlinear (vi = k-[e]0,4); the numerical value of the exponent (n = 0.4) argues in favour of a reaction occurring at the interface. The Lineweaver-Burk plots become linear if the substrate concentrations are based on the molar surface concentrations of the particles. The pH optimum for the reaction at the surface is displaced by 0.25 pH units towards the alkaline region (compared with ethanol as substrate). The activation energy of the reaction with tetradecanol beads as substrate is 30% lower than that for the ethanol oxydation.

Alcohol Oxidoreductases↗
PubMed1975

[Kinetic studies on long-chain alcohol turnover by yeast alcohol dehydrogenase within the transition from real solution to emulsion or suspension].

The enzymatic oxidation of hexanol, decanol, and tetradecanol by yeast alcohol dehydrogenase was studied. The enzyme was found to catalyze not only conversion in the real aqueous solution of the substrates, but also at the surface of undissolved substrate particles. The kinetic parameters varied on transition from the real solution to dispersion, in dependence on the chain length of the substrate.

Alcohol Oxidoreductases↗