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In tobacco callus, the induction of nicotine synthesis, which stimulates enzyme activities of the ornithine-methylpyrroline route (see the preceding paper), also leads to marked changes in the enzyme activities of the pyridine-nucleotide cycle. This cycle provides the metabolite (probably nicotinic acid) for condensation with methylpyrroline to produce(More)
The enzyme activities of the pyridine-nucleotide cycle, which transform nicotinic acid mononucleotide (NaMN) into NAD, have been characterized. The investigations were based on the extraction of protein, its purification on disposable gel-filtration columns, and determination of the enzymatic activities by high-performance liquid chromatography techniques.(More)
Exposure of primary rat hepatocytes and human HepG2 cells to allicin and ajoene resulted in the concentration-dependent inhibition of cholesterol biosynthesis at different steps of this metabolic pathway. At low concentrations of ajoene sterol biosynthesis from [14C]acetate in rat hepatocytes was decreased by 18% with an IC50-value of 15 microM, while(More)
The focus of in vitro dissolution testing during early development of modified release (MR) formulations is to provide predictive estimates of drug release in respect to in vivo performance of a drug product. However, there are enormous challenges in MR drug development to establish proper dissolution conditions for a predictive test. To overcome(More)
A procedure for the determination of nucleotide pools in plant tissue by HPLC is described. Sample preparation includes the extraction with 0.4 M HClO4, a purification step, which proved to be essential, on a disposable prepacked phenyl-bonded column, neutralization by KOH, and concentration by freeze-drying. The determination of a broad spectrum of(More)
An approach is described for evaluation of the specificity of basic polypeptides concerning the base pair composition of DNA. The polypeptides were covalently bound to CNBr activated agarose and two DNAs strongly different in base composition but of equal molecular weight were loaded and detached by a NaCl gradient. The difference in the NaCl(More)
Suspension cultured cells of Catharanthus roseus rapidly consume the inorganic phosphate of the medium and incorporate about 25% of it into their phospholipids. By three different methods of analysis it was shown that from these plant cells phosphorylated phosphatidylinositol species can be extracted; the mono- and diphosphorylated species were detected in(More)
Extraction of Nicotiana tabacum cell cultures, chromatography on DEAE-cellulose and gel filtration resulted in a homogeneous protein (Mr = 14500), which strongly reduces the hydrolysis of Escherichia coli DNA by DNase I. DNA degradation by micrococcal nuclease is not inhibited. The inhibitor protein interacts with DNase I in the absence of DNA, as(More)