3,415 research outputs found
Inhibition of Urease by Some Triazole, Urea, and Guanidine Derivatives
Series of aminotriazole, guanidine and urea derivatives were
prepared and tested as urease inhibitors. A greater part of the
tested compounds, all containing the sequence ressembling the substrate,
have shown an inhibitory effect on urease
Determination of Sulfhydryl Groups in Proteins and Enzymes by Indirect Amperometric Titration
R. Hamm and K. Hofmann1,2 described in 1965 a method for the determination of sulfhydryl groups by indirect amperometric titration of proteins with silver nitrate. This method is very useful because it can be applied to turbid solutions, suspensions or homogenates of miofibrills, muscle extracts or enzymes. We modified the above mentioned method using phenylmercuric acetate instead of AgN03 for the preincubation
Antifungal Activity and Inhibitory Effect on Urease of Some Organo-Mercuric Compounds
A number of aliphatic and aromatic organo-·mercuric compounds
of the general formula R-Hg-X, in which R represents
a n organic radical and X an anionic radical, were prepared. The
antifungal and inhibitory effect of the tested compounds
was compared by app ly1ng the aiuxa nographic diffusion method
and by measuring the degree of inhibition of urease. It was found
that the antifungal activity d epends mainly on the organic radical
R and that the antonic radical h as no effect on fungitoxicity
Grazing-Incidence Neutron Optics based on Wolter Geometries
The feasibility of grazing-incidence neutron imaging optics based on the Wolter geometries have been successfully demonstrated. Biological microscopy, neutron radiography, medical imaging, neutron crystallography and boron neutron capture therapy would benefit from high resolution focusing neutron optics. Two bounce optics can also be used to focus neutrons in SANS experiments. Here, the use of the optics would result in lower values of obtainable scattering angles. The high efficiency of the optics permits a decrease in the minimum scattering vector without lowering the neutron intensity on sample. In this application, a significant advantage of the reflective optics over refractive optics is that the focus is independent of wavelength, so that the technique can be applied to polychromatic beams at pulsed neutron sources
The Isolation and Kinetics of Lactoperoxidase
The catalatic and peroxidatic activities of lactoperoxidase
and horse-ra dish peroxidase are described. For measuring the
peroxidatic activity. pyrogallol was used as a hydrogen donor. A
manometric m ethod was used for the determination of the Km
value. The Km value for the catalatic reaction was calculated on
the basis of 0 2 evolved, a nd the peroxidatic reaction was calculated
on the basis of C02 evolved. In the catalatic reaction the
efficiency of lactoperoxidase and horse-radish peroxidase are of
the same order. The peroxidatic activity of lactoperoxidase is
higher than that of horse-radish peroxidase. The mechanism of
peroxidase action was interpreted as described by Chancet
Action of 1,6-Dimethyl-SB-(Bromoisonicotinoyl-Oxymethyl)-10a- Methoxyergoline (SermionR) on Some Molecular Processes in the Brain
The influence of SermionR on cellular protein synthesis in the
mouse brain was studied in vivo, after an intraperitoneal administration
of 50 microgram doses. The brain samples analyzed at different
intervals after drug treatment showed a short-term increase of
3H-Leucine incorporation into proteins, followed by a. gradual
decline of uptake. The latter reached control levels about 18 h
after drug administration. Under similar experimental treatments
Sermion had no effect on the synthesis of RNA catalyzed by Mg++-
ions; however, a slight stimulation of the Mn++- activated RNA
synthesis was obserwed.
Mice receiving i. p. injections of 50 micrograms of Sermion
showed an increased brain rnethyltransferase activity; the maximum
stimulation was observed one hour after drug treatment. In another
set of experiments the capacity of mouse brain preparations to
catalyze the methyl group incorporation into the exogenously added
transfer RNA (tRNA) was found to decrease with increasing age of
the animals; the addition of 10-4 M Sermion to the incubation medium
enhanced endogenous rnethylation, especially in the older
animals. On the other hand the capacity to methylate the exogenously
added heterologous tRNA was not effected by Sermion, irrespective
of the age of the animals.
In an attempt to understand the physiological relevance of the
biochemical effects of Sermion, we have carried out some studies
on the effect of this drug on conditioned learning in rats. The preliminary
data indicate that the drug is able to enhance the learning
quotients, however, more experiments are in progress to reach a
definitive conclusion
Determination of Sulfhydryl Groups in Proteins and Enzymes by Indirect Amperometric Titration
R. Hamm and K. Hofmann1,2 described in 1965 a method for the determination of sulfhydryl groups by indirect amperometric titration of proteins with silver nitrate. This method is very useful because it can be applied to turbid solutions, suspensions or homogenates of miofibrills, muscle extracts or enzymes. We modified the above mentioned method using phenylmercuric acetate instead of AgN03 for the preincubation
Identification and characterization of two novel primate-specific histone H3 variants, H3.X and H3.Y
The expression of a new histone variant H3.Y increases during cellular stress to regulate cell cycle progression and gene expression
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