Heide C Ludwig

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To understand the mechanism of signal propagation involved in the cooperative AMP inhibition of the homotetrameric enzyme pig-kidney fructose-1,6-bisphosphatase, Arg49 and Lys50 residues located at the C1-C2 interface of this enzyme were replaced using site-directed mutagenesis. The mutant enzymes Lys50Ala, Lys50Gln, Arg49Ala and Arg49Gln were expressed in(More)
The progression of malignancy from astrocytomas to glioblastomas remains clinically as well as histopathologically unpredictable. The focal adhesion kinase (FAK) and the proline-rich tyrosine kinase (Pyk2) show a high expression in glioma cell lines and have an influence on increased cell proliferation and migration of glioma cells in vitro and in vivo. The(More)
Heavy riboflavin synthase is a 1,000,000-Da protein catalyzing the last two reactions of riboflavin biosynthesis. The enzyme complex consists of 60 beta subunits (Mr = 16,200) and approximately three alpha subunits (Mr = 23,000). beta subunits were isolated and cleaved with cyanogen bromide. Fragments were isolated and further digested with trypsin and(More)
Glutathione S-transferases (GSTs) play a central role in a number of metabolic processes. Glutathione S-transferase T1 (GSTT1) is a polymorphic cytosolic enzyme and a member of the theta class of GSTs. Typical substrates for GSTT1 are industrial compounds, such as dichloromethane and ethylene oxide. It has been shown that also chemotherapeutic drugs such as(More)
Heavy riboflavin synthase from Bacillus subtilis is an enzyme complex consisting of approximately three alpha-subunits (Mr 23.5 X 10(3)) and 60 beta-subunits (Mr 16 X 10(3)). The enzyme has been crystallized from phosphate buffer in a hexagonal crystal modification that belongs to space group P6(3)22. The asymmetric unit of the crystal cell contains ten(More)
Selective treatment of pig kidney fructose 1,6-bisphosphatase with cyanate leads to the formation of an active carbamoylated derivative that shows no cooperative interaction between the AMP-binding sites, but completely retains the sensitivity to the inhibitor. By an exhaustive carbamoylation of the enzyme a derivative is formed that has a complete loss of(More)
BACKGROUND Fructose-1,6-bisphosphatase, a major enzyme of gluconeogenesis, is inhibited by AMP, Fru-2,6-P2 and by high concentrations of its substrate Fru-1,6-P2. The mechanism that produces substrate inhibition continues to be obscure. METHODS Four types of experiments were used to shed light on this: (1) kinetic measurements over a very wide range of(More)
The expression of aldolase A and B isoenzyme transcripts was confirmed by RT-PCR in rat kidney and their cell distribution was compared with characteristic enzymes of the gluconeogenic and glycolytic metabolic pathway: fructose-1,6-bisphosphatase (FBPase), phosphoenol pyruvate carboxykinase (PEPCK), and pyruvate kinase (PK). We detected aldolase A isoenzyme(More)
The unfolding and dissociation of the tetrameric enzyme fructose-1,6-bisphosphatase from pig kidney by guanidine hydrochloride have been investigated at equilibrium by monitoring enzyme activity, ANS binding, intrinsic (tyrosine) protein fluorescence, exposure of thiol groups, fluorescence of extrinsic probes (AEDANS, MIANS), and size-exclusion(More)
Heavy riboflavin synthase is a complex enzyme consisting of three alpha subunits and approximately 60 beta subunits. Ligand-binding studies were performed with a variety of substrate and product analogues by analytical ultracentrifugation and by equilibrium dialysis. Nonlinear binding curves indicate the involvement of non-equivalent binding sites which(More)