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Biomedical subjects

L Ehrenberg

Publications and source records attributed to L Ehrenberg.

At least 91 records · Page 5Linked to original sources
PubMed1975

Prophage inductive efficiency of alkylating agents and radiations.

The prophage inducing efficiency in E. coli K-12 (lambda) of a number of agents--alkylating agents and radiations--has been compared at a high survival of bacteria. The inducing effectiveness (per alkylation in DNA) and efficiency (compared with mutation frequency in E. coli Sd-4) was found to decrease in the order 2-hydroxyethylating agents (2-hydroxyethyl methanesulphonate and ethylene oxide) greater than isopropyl methanesulphonate approximately equal to methyl methanesulphonate greater than ethylating agents (diethyl sulphate, ethyl methanesulphonate). The low inducing activity of the ethylating agents could not be explained with respect to their reactivity towards targets of differing nucleophilicity, nor could the effectiveness in mutagenicity or the ability to break the chromosomes in the presence of metal ions be invoked. The high inducing efficiency of hydroxyalkylating agents may be related to their ability to break DNA strands.

Alkylating Agents↗
PubMed1975

Cyclization of uridine monophosphate by diethyl pyrocarbonate.

Reaction between diethyl pyrocarbonate and uridine 2'-phosphate or uridine 3'-phosphate leads to the formation in high yields of uridine 2':3'-cyclic phosphate. This reaction product was identified in experiments involving (a) ultraviolet spectrophotometry, (b) paper chromatography, (c) high voltage paper electrophoresis at both pH 3.5 and 7.4, (d) acid hydrolysis, and (e) digestion with pancreatic ribonuclease.

Alkaline Phosphatase↗
PubMed1973

Nuclear magnetic relaxation study of tobacco mosaic virus solutions.

The molecular order of water in liquid-crystalline 5-28% tobacco mosaic virus (TMV) solutions was studied by proton spin-spin, spin-lattice, and translational self-diffusion coefficient measurements at various concentrations as well as by deuteron D(2)O nuclear magnetic resonance (NMR) studies. The results show that the average H(2)O molecule spends less than 1% of its time in an ordered state bound to the TMV backbone. The protons on the TMV molecules themselves, on the other hand have a very short spin-spin relaxation time T(2) of about 20 mus, demonstrating the existence of a high degree of liquid-crystalline order.

Crystallization↗
PubMed1973

Isolation of substances that stimulate RNA synthesis from red kidney bean: their activities in lymphocytes and Escherichia coli.

An extract from red kidney beans (Phaseolus vulgaris) was fractionated with respect to RNA synthesis-stimulating activity. The activity of the fractions was tested in chicken-spleen lymphocytes cultured in serum-free medium and in plasmolyzed E. coli cells. Lymphocyte-stimulating activity was found in a fraction called F III. This fraction contained protein and orcinol-positive carbohydrate. The protein (called F III p) responsible for the observed activity was separated from the contaminating carbohydrate by acid precipitation. F III p appears to belong to the group of well-known mitogens of high molecular weight present in red kidney beans. A bacteria-stimulating factor was found in a fraction called F V. This factor strongly stimulated RNA synthesis in the bacterial system, and had a weak stimulating effect in the lymphocyte system. In plasmolyzed E. coli cells, F V counteracted the inhibiting effect of rifampicin on RNA synthesis.

Animals↗