C-terminal processing of yeast Spt7 occurs in the absence of functional SAGA complex

Background  

Spt7 is an integral component of the multi-subunit SAGA complex that is required for the expression of ~10% of yeast genes. Two forms of Spt7 have been identified, the second of which is truncated at its C-terminus and found in the SAGA-like (SLIK) complex.     

Die Trennung des Silbers von Blei durch F?llung als Silbersaccharinat

Zusammenfassung Durch FÄllung des Silbers mit Dowex-I-saccharinat als Silbersaccharinat können im SÄulenverfahren Trennungen von Blei bis zum VerhÄltnis AgPb=1200 erzielt werden. Kupfer und Wismut stören nur, wenn sie in gro\en Mengen vorliegen. Das in der SÄule abgeschiedene Silbersaccharinat wird mit Ammoniak gelöst.     

Activation of topoisomerase II during partial purification by heparin-Sepharose chromatography

Partial purification of topoisomerase II from small samples (10(7)-10(8) cells) of human leukaemic cells was achieved by isolation of cell nuclei, hyper-osmotic extraction of nuclear proteins, sorption of nuclear proteins by heparin-Sepharose and elution with potassium phosphate. Similar results were obtained by gradient and batchwise elution. The calatylic activity of topoisomerase increased ca. eightfold after removal of ca. 95% of the contaminating nuclear proteins. The conserved enzymatic activity after partial purification indicates that the enzyme was not damaged. The half-life of enzymatic activity is increased by the chromatographic procedure. Owing to its high yield and technical simplicity, this could be a candidate procedure for the study of topoisomerase II in patient-derived blood samples.     

Use of anion-exchange chromatography and chromatofocusing to reveal the structural and functional heterogeneity of topoisomerase II in a HL-60 cell line resistant to multi-drug treatment.

Fractionation of nuclear extracts from a multi-drug-resistant subclone of the human promyelocytic subline HL-60 by anion-exchange chromatography and chromatofocusing resolves at least two different subtypes of topoisomerase II, which are not identical to the known alpha- and beta-forms of the enzyme because both forms are contained in each subtype. The two subtypes are present in about equal proportions and differ remarkably with respect to the optimum of reaction and sensitivity to m-amsacrine and orthovanadate. Both subtypes are highly insensitive to etoposide inhibition in vitro.     

Investigation of molecular order and phase transitions of smectic poly(ester imide)s by means of small-angle X-ray scattering

The molecular order and phase transitions of two smectic poly(ester imide)s based on aminobenzoic acid trimellitimide (PEI 1) or aminocinnamic acid trimellitimide (PEI 2) and α,ω-dihydroxydodecane were investigated by X-ray scattering. During cooling, the polymers pass through monotropic smectic liquid-crystalline (LC) phases (S_A, S_C), which transform into higher-ordered smectic-crystalline phases (S_E, S_H). The smectic layer structure of about 3 nm gives rise to a sharp reflection at 2θ ≅ 3°. Peak shape analysis and analysis of the interface distribution function revealed long-range longitudinal correlation among the mesogens in the LC phase but short-range lateral correlation. The development of a broad reflection in the small-angle X-ray scattering (SAXS, 2θ < 1°) indicates the formation of a lamellar two-phase system. The long-period changes reversibly between 10 and 30 nm with increasing temperature. The crystalline lamellae comprise a number of smectic-crystalline layers with packed mesogens, while the noncrystalline interlamellar regions keep their smectic-LC order. In the metastable S_B phase, formed during annealing of quenched PEI 1, the diffuse SAXS indicates a random distribution of small, probably fringed, crystals with hexagonal-packed mesogens. In the lamellar S_E and S_H phases, tie molecules play an important role, but chain folding cannot be excluded. Received: 16 July 1999/Accepted: 28 April 2000