The aim of the present study was to investigate homoharringtonine alkaloid effect on: (i) the nonenzymatic and eEF‐1‐dependent Phe‐tRNAphe binding to poly(U)‐programmed human placenta 80 S ribosomes; (ii) diphenylalanine synthesis accompanying nonenzymatic Phe‐tRNAphe binding; and (iii) acetylphenylalanyl‐puromycin formation. Neither nonenzymatic nor eEF‐1‐dependent Phe‐tRNAphe binding were noticeably affected by the alkaloid, whereas diphenylalanine synthesis and puromycin reaction were strongly inhibited by homoharringtonine. It has been proposed that the site of homoharringtonine binding on 80 S ribosomes shouldoverlap or coincide with the acceptor site of the ribosome.
DNA polymerase alpha from germinated wheat embryos was purified by ammonium sulphate fractionation, chromatography on DEAE-Toyopearl, followed by phosphocellulose and heparin Sepharose columns. The specific activity of the purified enzyme was more than 60,000 units/mg. It belongs to the alpha-type according to the large molecular mass, high sensitivity to NEM, aphidicoline, 200 mM KCl, low sensitivity to ethidium bromide and the absence of inhibition by ddTTP. DNA polymerase alpha consists of four subunits as shown by SDS-PAGE and seems to be homogeneous under non-denaturing conditions.
We have studied the action of the alkaloid cytisine on protein synthesis of plants. The alkaloid has been shown to have no effect on mRNA translation.At the same time it considerably decreases the release of mRNP particles from nuclei.Protein synthesis; mRNA transport: Cytisine
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