Luis A Jurado

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Activation of calcineurin by Mn2+ and Mg2+ was compared using a heavy atom isotope analogue of the substrate p-nitrophenyl phosphate (pNPP). Heavy atom isotope effects were measured for Mg2+ activation and compared to published results of the isotope effects with Mn2+ as the activating metal. Isotope effects were measured for the kinetic parameter Vmax/Km(More)
As a possible probe for metal activation of calcineurin, Tb3+ was tested for effects on calcineurin activity. Calcineurin was activated by Tb3+ with the following kinetic parameters estimated: k(cat) = 0.78 +/- 0.02 sec(-1), Km(pNPP) = 32.6 +/- 1.8 mM, and K(act)(Tb3+) = 0.08 +/- 0.03 mM. Terbium luminescence was demonstrated in the presence of the(More)
DNA-affinity chromatography has been used for the purification of DNA-binding proteins that control various cellular processes. There have been improvements in coupling methods and choice of supports over the years. The procedure for coupling 5'-aminoethyl-(dT)18 to silica activated with N-hydroxysuccinimide and a carbodiimide has been described. Also, the(More)
A sequence-specific DNA that binds EcoRI endonuclease was immobilized on glycidioloxypropyl-silica and Sepharose by cyanogen bromide (CNBr)-activated coupling. Elution of bound enzyme by conventional affinity strategies (increase of salt concentration) or by catalysis-induced elution (adding a Mg2+ cofactor required for catalysis) was compared. Greater(More)
A new coupling strategy using pre-packed diol-silica supports to obtain affinity columns for high-performance affinity chromatography (HPAC) is described. These columns were prepared by "in flow" activation in which solutions containing anhydrous solutions of CNBr and triethylamine are separately pumped to a mixer and then onto a pre-packed diol-silica(More)
To obtain silica supports for high-performance affinity chromatography, a method of preparing CNBr-activated diol-silica under anhydrous conditions was developed. Activation of the silane-derived hydroxyls with cyanogen bromide and triethylamine was optimized and demonstrated to efficiently couple several amino ligands (tryptophan, 6-aminohexyl-Cibacron(More)
Catalytic chromatography exploits both specific biological affinity and catalytic specificity to selectively purify enzymes. Two different applications are presented. Purification of EcoRI restriction endonuclease to apparent homogeneity was accomplished in a single step with significantly greater yield and purification than was obtained with affinity(More)
Intracellular Ca2+ is normally maintained at submicromolar levels but increases during many forms of cellular stimulation. This increased Ca2+ binds to receptor proteins such as calmodulin (CaM) and alters the cell's metabolism and physiology. Calcium-CaM binds to target proteins and alters their function in such a way as to transduce the Ca2+ signal.(More)