Descripción: Fil:González, N.S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Descripción: Fructokinase (ATP:d-fructose-1-phosphate transferase, EC 2.7.1.3) from rat liver has been purified 400-fold. The purification procedure involves an acid treatment, a heat step at 65°, (NH4)2SO4 fractionation, chromatography on Sephadex G-100 and finally (NH4)2SO4 extraction. The enzyme appears nearly homogenous by density gradient centrifugation but gives a single peak in sedimentation velocity analysis. Purified liver fructokinase has a Km of 0.46-0.80 mM for fructose and 1.56-1.33 mM for MgATP at a K+ concentration of 0.4 and 0.1 M, respectively. The enzyme also phosphorylates l-sorbose and d-tagatose. No difference could be found in the phosphorylation of the pyranose and furanose forms of fructose. The enzyme is inhibited by p-chloromercuribenzoate and is stable up to 50-55°. © 1971.

Descripción: 1. 1. The sensitivity of partially purified low Km, phosphodiesterase (PDE) from Mucor rouxii to pharmacological agents and cAMP analogs was studied. The IC50 obtained were compared with those reported for PDEs from higher eukaryotes. 2. 2. The best inhibitors of the hydrolysis of 1 gmM cAMP were SQ 65.442 (IC50, c 10 μM), dipyridamol and CI 930. cGMP was not an inhibitor (IC50 > 1000 μm). 3. 3. The cAMP analogs were tested as inhibitors of the hydrolysis of 0. l μM cAMP. 8-Aminohexylamino cAMP was the best inhibitor with an IC50 of c 1 μM. 4. 4. A sedimentation profile of Mucor PDE was assayed in the presence of several pharmacological inhibitors and eAMP analogs. No isoforms with different sensitivity towards the inhibitors were detected. Forms with slightly different behaviour towards some cAMP analogs were observed. © 1990.