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Biomedical subjects

E Yagil

Publications and source records attributed to E Yagil.

45 records · Page 3Linked to original sources
PubMed1971

On the relation between effector concentration and the rate of induced enzyme synthesis.

The Jacob and Monod scheme for the regulation of enzyme formation leads to the following relation between the relative rate of enzyme synthesis alpha and cellular effector concentration E (the lower sign is for repressible systems): log (alpha/1 - alpha - alpha(b)) = +/- n log [E] + log alpha(b) +/- log K(1). This equation permits linear plotting of experimental data and the evaluation of three quantities: n, the number of effector molecules combining with a repressor molecule, K(1), the dissociation constant of this interaction and K(2)/R(t), the ratio of repressor-operator dissociation constant to total repressor concentration. Measurements on the repression of alkaline phosphatase in Escherichia coli as a function of phosphate concentration are reported and fit the proposed equation with n = 1, indicating that the binding of a single phosphate to the repressor species may be sufficient to cause repression. K(1) of this interaction was found to be 0.58 +/-0.11 x 10(-3) M. The available data regarding the enzymes of the lac operon in a variety of E. coli strains, and several other enzymes are analyzed. It is confirmed that the lac repressor interacts with 2 isopropyl thiogalactoside (IPTG) molecules to relieve repression with a K(1) = 50 +/-20 x 10(-12) M(2). In some strains, separate binding constants for the first and second IPTG molecules can be evaluated.

Alkaline Phosphatase↗
PubMed1970

Effect of adenosine and deoxyadenosine on the incorporation and breakdown of thymidine in Escherichia coli K-12.

Deoxyadenosine (AdR) and adenosine (AR) enhance the incorporation of thymidine (TdR) into bacterial deoxyribonucleic acid (DNA) by the inhibition of TdR phosphorolysis in vivo. Neither of the purine nucleosides has an effect on the reaction catalyzed by TdR phosphorylase in vitro. AdR induces TdR phosphorylase and both purine nucleosides induce purine nucleoside phosphorylase. AR can stimulate uptake of more TdR into bacterial DNA than AdR.

DNA, Bacterial↗
PubMed1969

Decay of normal and 5-fluorouracil-substituted messenger ribonucleic acid of alkaline phosphatase in Escherichia coli.

The decay of alkaline phosphatase messenger ribonucleic acid (mRNA) in Escherichia coli was studied in cells sensitized to actinomycin D by ethylenediaminetetra-acetate treatment. It was found that in the wild-type strain (K-10) as well as in a nonsense mutant (S26C200), which is phenotypically reversible by treatment with 5-fluorouracil, mRNA decays with a half-life of 2.0 to 2.5 min. Similarly, in a 3-min pulse of labeled 5-fluorouracil, 70% of the incorporated analogue is contained in the labile RNA fraction decomposing with a half-life of 1.8 min.

Alkaline Phosphatase↗