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Hen egg-white lysozyme (HEWL) was the first enzyme to have its three-dimensional structure determined by X-ray diffraction techniques. A catalytic mechanism, featuring a long-lived oxocarbenium-ion intermediate, was proposed on the basis of model-building studies. The 'Phillips' mechanism is widely held as the paradigm for the catalytic mechanism of(More)
Software development in a small development team is a challenge, as people have to fulfill several roles, which in larger groups would have separate, dedicated people for the work. To help small development teams to organize their activities, ISO/IEC standardization body has developed the standard ISO/IEC 29110, Lifecycle profiles for Very Small Entities.(More)
Cytochrome P450 (CYP) enzymes represent a large superfamily that displays extraordinarily diverse substrate specificities. After a concise review about CYPs of the CYP1A subfamily, which plays a crucial role in procarcinogen activation, this paper presents segment-directed mutagenesis. This approach generates a library of random combinatorial mutants(More)
In the presence of its allosteric activator GDP, the major phosphofructokinase-1 from Escherichia coli K12 follows Michaelis-Menten kinetics. The kinetic behavior observed at steady-state using different concentrations of the substrates ATP and fructose-6-phosphate and the pattern of inhibition by the substrate analogs adenylyl-(beta,(More)
Two glycopeptides were obtained from alpha 1-protease inhibitor after extensive pronase digestion and chromatography on Bio-Gel P-10 and concanavalin A-Sepharose. these glycopeptides were characterized by compositional analysis and sequential exoglycosidase digestion followed at each step by methylation analysis. The partially methylated alditol acetates(More)
Stepwise increments of the concentration of 2-difluoromethylornithine (DFMO), a mechanism-based irreversible inhibitor of mammalian ornithine decarboxylase (ODC), resulted in a selection of cultured human IgG-myeloma cells (Sultan cell line) capable of growing in the presence of up to 3 mM-DFMO. This capacity was associated with 10-fold increase in ODC(More)
Three bis(guanylhydrazones) (those of methylglyoxal, glyoxal and ethylglyoxal) were compared for their affinity for the putative polyamine carrier and for their cellular retention in L1210 mouse leukaemia cells. All the bis(guanylhydrazones) inhibited equally effectively the uptake of spermidine by the tumour cells, indicating that the compounds had roughly(More)
Diethylglyoxal bis(guanylhydrazone) (DEGBG), a novel analog of the antileukemic agent methylglyoxal bis(guanylhydrazone) (MGBG) was synthesized. It was found to be the most powerful inhibitor of yeast S-adenosylmethionine decarboxylase (AdoMetDC) so far studied (Ki approx. 9 nM). This property, together with the finding that the compound is a weaker(More)
Chronic exposure of a human myeloma cell line to dexamethasone resulted in a selection of cells resistant to the growth-inhibitory action of the glucocorticoid. Upon acute exposure of the parental myeloma cells to dexamethasone growth inhibition was associated with depression of ornithine decarboxylase (ODC, EC 4.1.1.17) activity. However, in cells adapted(More)
The first generation of yeast expression systems relies on inducible expression cassettes borne by multicopy plasmids for production of unmodified human P450s and on the endogenous NADPH-P450 reductase to support activities. A second generation of engineered yeast involved targeted genomic modifications allowing overexpression of the yeast reductase and(More)