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M Schülein

Publications and source records attributed to M Schülein.

42 records · Page 3Linked to original sources
PubMed1992

Comparison of structure and activities of peroxidases from Coprinus cinereus, Coprinus macrorhizus and Arthromyces ramosus.

Initial structural and kinetic data suggested that peroxidases from Coprinus cinereus, Coprinus macrorhizus and Arthromyces ramosus were similar. Therefore they were characterized more fully. The three peroxidases were purified to RZ 2.5 and showed immunochemical identity as well as an identical M(r) of 38,000, pI about 3.5 and similar amino acid compositions. The N-termini were blocked for amino acid sequencing. The peroxidases had similar retention volumes by anion-exchange and gel-filtration chromatography. All peroxidases showed multiple peaks by Concanavalin A-Sepharose chromatography. The Concanavalin A-Sepharose profiles were different and depended furthermore on a fermentation batch. Tryptic peptide maps were very similar except for one peptide. This peptide contained an N-linked glycan composed of varying ratios of glucosamine and mannose for the three peroxidases. Rate constants and their pH dependence were the same for the three peroxidases using guaiacol or iodide as reducing substrates. We conclude that peroxidases from Coprinus cinereus, Coprinus macrorhizus and Arthromyces ramosus are most likely identical in their amino acid sequences, but deviate in glycosylation which, apparently, has no influence on the reaction rates of the enzyme. We suggest, that the Coprinus fungi express one peroxidase only in contrast to the lignin-degrading white-rot Basidiomycetes, which produce multiple peroxidase isozymes.

Amino Acid Sequence↗
PubMed1976

Biochemical changes during regression and regrowth of hormone-dependent GR mouse mammary tumors.

Discontinuation of recommencement of estrone-progesterone treatment causes regression and regrowth, respectively, of transplantable hormone-dependent GR mouse mammary tumors. This tumor model was found convenient for the demonstration of hormonal responses in hormone-dependent mouse mammary tumor cells. Tumor regression was palpable 2 days after discontinuation of hormonal treatment and tumors reached half their size within 3-6 days. At this point, hormones were readministered and 2-4 days later the tumors had grown to their preregression size. In the growing and regressing tumor we have investigated: (1) the content of RNA, DNA and protein per g wet weight, (2) in vivo incorporation for 45 min of 32P-orthophosphate into RNA and DNA and the 35S-methionine incorporation into protine; (3) SDS polyacrylamide gel electrophoresis of soluble proteins after in vivo incorporation of 14C- and 3H-leucine. The RNA content per g wet weight was found to decrease during regression and to increase during regrowth. DNA and protein content showed no variation. RNA/DNA ratio thus varied in parallel to the RNA content. The precuursor incorporation into all three macromolecular species decreased during regression. The incorporation into DNA showed the most pronounced decrease. After readministration of hormones, regrowth was accompanied by a rapid increase in precursor incorporation into RNA, while the incorporation into DNA showed a lag of 1 to 2 days. SDS polyacrylamide gel electrophoresis was carried out with soluble proteins labelled in vivo with 14C- and 3H-leucine during regression and regrowth, respectively. No differences in 14C/3H ratios could be demonstrated for the major fractions detectable in the electropherogram.

Animals↗
PubMed1975

High affinity oestradiol receptors and the activity of glucose-6-phosphate dehydrogenase and lactose synthetase in mammary carcinomata of postmenopausal women.

The determination of hormone inducible proteins in endocrine tumours may yield information about the presence of hormone dependent tumour cells. We have estimated the high affinity oestradiol binding capacity in primary mammary carcinomata of 57 postmenopausal patients. Glucose-6-phosphate dehydrogenase and lactose synthetase are known from animal experiments to be hormone inducible. Therefore, in biopsies of sufficient size the activity of glucose-6-phosphate dehydrogenase (47 pateints) and lactose synthetase (23 patients) was also studied. It was found that biopsies with high binding capacity also showed high activities of glucose-6-phosphate dehydrogenase and lactose synthetase A protein (galactosyl transferase). No lactose synthetase B protein (alpha-lactalbumin) has been discovered in the tumours. The present observations may be considered suggestive evidence of a relationship between high oestradiol binding capcity and high activities of the two enzymes on the one hand and hormone dependence of the tumour on the other. However, further clinical studies are required before final conclusions in this respect can be drawn.

Biopsy↗