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K Lübke

Publications and source records attributed to K Lübke.

18 recordsLinked to original sources
PubMed1995

Direct detection of recombinant gene expression by two genetically engineered yeasts in soil on the transcriptional and translational levels.

The expression of a recombinant gene by yeasts seeded into soil samples was directly measured by analyzing transcripts and gene product occurrences in soil extracts. Two yeast species, Saccharomyces cerevisiae WHL292 and Hansenula polymorpha LR9-Apr4, both engineered by a synthetic gene sequence encoding the mammalian peptide aprotinin, produced and secreted this peptide in batch cultures at concentrations of 90 and 64 ng ml-1, respectively. In S. cerevisiae, the aprotinin gene was located on plasmid p707 and expressed constitutively. H. polymorpha carried the gene chromosomally integrated, and its expression was inducible by methanol. To detect aprotinin transcripts, cells were directly lysed in the soil samples and the crude lysates were hybridized to oligo(dT)-coated magnetized polystyrene beads (Dynabeads). After separation and purification in a magnetic field, aprotinin mRNA was detected by reverse transcriptase PCR with aprotinin gene-specific primers. Transcripts from 10 cells g of soil-1 were sufficient for detection. When 10(7) cells of S. cerevisiae were inoculated into soil, aprotinin mRNA was detectable during the first 4 days. Addition of methanol and a combined nutrient solution was necessary to induce aprotinin gene expression of H. polymorpha in soil. Aprotinin could be detected directly in soil extracts by an indirect enzyme-linked immunosorbent assay with monoclonal aprotinin-specific antibodies. The detection threshold was 45 pg g of soil-1. In presterilized soil inoculated with S. cerevisiae (10(6) CFU g-1), aprotinin accumulated during the first 10 days to 12 ng g of soil-1 and then remained constant.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1978

The stability of A1,B29-adipoylinsulin to chemical and enzymatic degradation.

The degradation of A1,B29-adipolyinsulin by partial hydrolysis, by disulphide-bond exchange, by chymotrypsin and by a cytosolic enzyme fraction of rat liver was measured and compared with that of A1,B29-diacetylinsulin and insulin. The cross-linked insulin is, in general, more resistant than insulin itself or the diacetylated derivative. However, in the case of enzymatic degradation, A1,B29-diacetylinsulin resembles more the cross-linked derivative than insulin. This provides evidence that the properties of A1,B29-adipoylinsulin could not in all circumstances be attributed to its 'proinsulin-like' structure.

Animals↗
PubMed1977

Radioimmunological determination of cyproterone acetate.

A sensitive and specific radioimmunoassay for cyproterone acetate in serum has been developed. Antiserum was raised in rabbits by immunization with a conjugate of cyproterone acetate-11 alpha-hemisuccinate and bovine serum albumin. Radioactive tracers with high specific activities were synthesized by coupling the hemisuccinate with [3H]-tyrosine methyl ester of [125I]-iodohistamine. Competition studies with substances structurally related to cyproterone acetate have revealed that the structures of ring A and B are mainly responsible for binding to the antibody.

Antibody Specificity↗
PubMed1976

Hormone receptors.

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Adrenal Cortex↗
PubMed1976

A method for radioimmunological assay of glisoxepide (author's transl).

A radioimmunoassay for the antidiabetic drug 3-(4-[beta-(5-methyl-isoxazol-3-carboxyamido)-ethyl]-benzenesulfonyl)-ureido-piperidine-4-carboxic acid (glisoxepide, I, Pro-Diaban) is described. Antisera were obtained by immunizing rabbits with a piperidine carboxylic acid analogue of glisoxepide coupled to bovine serum albumine. The carboxylic acid analogue coupled to [3H]-1-tyrosine methyl ester was used as the tracer. Antisera with high sensitivity were obtained. With some glisoxepide analogues the specificity of the antisera was investigated. For good binding the isoxazole and the benzene ring as well as the appropriate distance between both rings are essential. The assay can be carried out without extraction of the compound from the serum. Dextran coated charcoal is used for separation of free and bound glisoxepide.

Cross Reactions↗