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J Wrzesiński

Publications and source records attributed to J Wrzesiński.

4 recordsLinked to original sources
PubMed2001

Effective charge of the (pi)h(11/2) orbital and the electric field gradient of Hg from the Yrast structure of 206Hg.

The gamma-ray decay of excited states of the two-proton hole nucleus, 206Hg, has been identified using Gammasphere and 208Pb+238U collisions. The yrast states found include a T(1/2) = 92(8) ns 10(+) isomer located above the known 5(-) isomer. The B(E2;10(+)-->8(+)) strength is used to derive the quadrupole polarization charge induced by the h(11/2) proton hole. Also, the implied quadrupole moment has been used to provide an absolute scale for the electric field gradient of Hg in Hg metal.

Journal Article↗
PubMed1998

A cell-free yellow lupin extract containing activities of pseudouridine 35 and 55 synthases.

Plant cytoplasmic tyrosine tRNA was pseudouridylated at three different positions: 35, 39 and 55. These pseudouridines were introduced by three different enzymes--pseudouridine synthases. Variants of the Arabidopsis thaliana pre-tRNA(Tyr) were constructed that allow to monitor specifically pseudouridylation at different nucleotide positions. Using such RNAs to assay pseudouridine synthesis we have prepared an extract from Lupinus luteus cv. Ventus seeds containing activities of at least psi35 and psi55 synthases. This is the first report describing the preparation of the lupin seed extract that specifically modifies plant pre-tRNA(Tyr) transcribed by T7 RNA polymerase. U35 is converted to psi35 only in an intron-dependent manner, while pseudouridylation of U55 is insensitive to the presence or absence of an intron.

Arabidopsis↗
PubMed1989

Specificity and mechanism of the cleavages induced in yeast tRNAPhe by magnesium ions.

The specificity of magnesium ion-induced hydrolysis of yeast tRNAPhe in solution was studied as a function of the excess of Mg(II) ions and pH. The major cuts at phosphates 16 and 20 as well as minor cleavages at phosphates 17, 18, 21, 34 and 36 occur at all pH values in the range of 8.0-9.5, and at a molar excess of magnesium ions over the tRNA ranging from 125 to 5000. In yeast tRNA(Phe)-Y the efficiency of the anticodon and D-loop cleavages is considerably decreased while the differently modified Y-base of yellow lupin tRNA(Phe) lowers the specificity of the weak anticodon loop cleavages. The mechanism of the Mg(II)-induced cleavages is discussed on the basis of yeast tRNA(Phe) crystal structure data, and the two major D-loop cleavages are thought to be effected from two distinct magnesium binding sites. The possibility of probing the environments of magnesium binding sites in tRNAs by the induced cleavages is demonstrated, and the relevance of magnesium-induced tRNA cleavages to RNA catalysis is discussed.

Fabaceae↗