cloning and expression of the l-phenylalanine dehydrogenase gene, from b. sphaericus in e. coli were done. the gene was cloned in the vector pet16b and transformed into e. coli bl21 (de3). the functional form of the l-phenylalanine dehydrogenase enzyme was purified by affinity purification techniques, taking advantage of the ability of this enzyme to bind to the nucleotide site affinity dye, re...

An acetylcholine hydrolyzing enzyme was prepared and purified (40 times) from dwarf bean hypocotyl hooks. The purity of the enzyme was proved by polyacrylamide gel electrophoresis. The molecular weight of the enzyme was determined to be 65,000 daltons. Enzyme activity was the highest at pH 8.0 and between 30 and 36 C. The enzyme had an apparent affinity constant (K(m)) for acetylcholine of 460/...

Cytidine deaminase (cytidine aminohydrolase, EC 3.5.4.5) has been purified approximately 160-fold from extracts of Escherichia coli B. The enzyme shows constant activity between pH 6 and 11. No significant change in rate is observed when DzO replaces water as the solvent. In addition to the deamination of cytidine, the purified deaminase catalyzes slow hydrolysis of N4-methylcytidine. The enzym...

This is a study of high-affinity glucose uptake in Aspergillus niger and the effect of disruption of a high-affinity monosaccharide-transporter gene, mstA. The substrate saturation constant (K(s)) of a reference strain was about 15 microM in glucose-limited chemostat culture. Disruption of mstA resulted in a two- to fivefold reduction in affinity for glucose and led to expression of a low-affin...

A cytokinin-binding protein has been isolated from wheat germ via ammonium sulfate precipitation, carboxymethyl Sephadex chromatography, and affinity chromatography on a column substituted with a derivative of kinetin riboside. On Sephadex G-200, the protein migrated with an apparent molecular weight of 122,000 daltons. The dissociation constant for kinetin was determined by equilibrium dialysi...

125I-labeled TNF(LuKII) (tumor necrosis factor) binds specifically to human and mouse cell lines sensitive to the cytotoxic effect of TNF, but not to cells made resistant to TNF. TNF-sensitive cells have cell surface receptors with a high affinity for TNF(LuKII). Mouse TNF competes with TNF(LuKII) for receptor binding. Scatchard analysis of the binding data yielded linear plots and suggests tha...

Cytidine deaminase (cytidine aminohydrolase, EC 3.5.4.5) has been purified approximately 160-fold from extracts of Escherichia coli B. The enzyme shows constant activity between pH 6 and 11. No significant change in rate is observed when DzO replaces water as the solvent. In addition to the deamination of cytidine, the purified deaminase catalyzes slow hydrolysis of N4-methylcytidine. The enzym...

Binding of alpha-bungarotoxin, labeled with 125I, has been studied in detergent extracts and affinity purified acetylcholine receptor from rat cerebral cortex. Binding to detergent extracts is saturable and appears to be due to one class of binding sites present at a level of 0.27 pmol/mg of protein. The association constant is 2 X 10(7) liters mol-1 . Competition with cholinergic ligands indic...

Existing data in the literature indicate that alpha 2-adrenergic receptor agonists have a profound hypotensive action, that sodium attenuates the affinity of alpha 2-adrenergic receptors for agonists, that the location of these receptors in the central nervous system is mainly at the sites of cardiovascular regulation, and that these sites exert a constant tonic inhibition of sympathetic vasoco...

Chronic infusion of morphine to guinea pigs produced selective changes in mu agonist binding properties in cerebrocortical membrane preparations. Employing the mu-selective opioid agonist [D-Ala2,MePhe4,Gly-ol5]enkephalin (DAMGO) in direct binding studies and in competition of labeled antagonist binding, we found that the major changes were a decrease in the number of sites with high affinity f...