5'-bromoacetamido-5'-deoxyadenosine. A novel reagent for labeling adenine nucleotide sites in proteins. 1983

B R Samant, and F Sweet

We have synthesized and characterized 5'-bromoacetamido-5'-deoxyadenosine (5'-BADA), a new reagent for labeling adenine nucleotide binding sites in enzymatic and regulatory proteins. 5'-BADA possessed exceptionally high solubility and stability in aqueous buffers between pH 5.0 and 8.6 at 25 degrees C. A Dixon plot of data from enzyme kinetic measurements showed that 5'-BADA is a competitive inhibitor of NADH oxidation by 3 alpha,20 beta-hydroxysteroid dehydrogenase with a Ki value of 11.8 mM. This compares with a Ki value of 10 mM for adenosine under similar experimental conditions. Incubating 5'-BADA with a 3 alpha,20 beta-hydroxysteroid dehydrogenase at pH 7.0 and 25 degrees C caused simultaneous loss of both 3 alpha and 20 beta activity. The enzyme inactivation reaction proceeded by a first order kinetic process. The rates of enzyme inactivation as a function of 5'-BADA concentration obeyed saturation kinetics. 2-Bromoacetamide, at ten times the maximum concentration of 5'-BADA, had no measurable effect on enzyme activity during 25 h of incubation. NADH and AMP protected 3 alpha,20 beta-hydroxysteroid dehydrogenase against inactivation by 5'-BADA. The results suggest that 5'-BADA inactivates the enzyme by irreversibly binding to the adenine domain of the NADH cofactor binding region at the catalytic site of 3 alpha,20 beta-hydroxysteroid dehydrogenase. Irreversible binding follows from an alkylation reaction between the bromoacetamido side chain of 5'-BADA and an amino acid at or near the enzyme catalytic site. 5'-BADA is presented as a new reagent for selectively labeling amino acid residues at the adenine nucleotide binding sites of enzymatic and regulatory proteins.

UI MeSH Term Description Entries
D007202 Indicators and Reagents Substances used for the detection, identification, analysis, etc. of chemical, biological, or pathologic processes or conditions. Indicators are substances that change in physical appearance, e.g., color, at or approaching the endpoint of a chemical titration, e.g., on the passage between acidity and alkalinity. Reagents are substances used for the detection or determination of another substance by chemical or microscopical means, especially analysis. Types of reagents are precipitants, solvents, oxidizers, reducers, fluxes, and colorimetric reagents. (From Grant & Hackh's Chemical Dictionary, 5th ed, p301, p499) Indicator,Reagent,Reagents,Indicators,Reagents and Indicators
D007700 Kinetics The rate dynamics in chemical or physical systems.
D011485 Protein Binding The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments. Plasma Protein Binding Capacity,Binding, Protein
D011506 Proteins Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein. Gene Products, Protein,Gene Proteins,Protein,Protein Gene Products,Proteins, Gene
D003349 Cortisone Reductase An enzyme that catalyzes the interconversion of a ketone and hydroxy group at C-20 of cortisone and other 17,20,21-trihydroxy steroids. EC 1.1.1.53. 20-beta-Hydroxysteroid Dehydrogenase,3 alpha,20 beta Hydroxysteroid Dehydrogenase,20 beta Hydroxysteroid Dehydrogenase,Dehydrogenase, 20-beta-Hydroxysteroid,Reductase, Cortisone
D003839 Deoxyadenosines Adenosine molecules which can be substituted in any position, but are lacking one hydroxyl group in the ribose part of the molecule. Adenine Deoxyribonucleosides,Adenylyldeoxyribonucleosides,Deoxyadenosine Derivatives,Deoxyribonucleosides, Adenine,Derivatives, Deoxyadenosine
D000227 Adenine Nucleotides Adenine Nucleotide,Adenosine Phosphate,Adenosine Phosphates,Nucleotide, Adenine,Nucleotides, Adenine,Phosphate, Adenosine,Phosphates, Adenosine
D000345 Affinity Labels Analogs of those substrates or compounds which bind naturally at the active sites of proteins, enzymes, antibodies, steroids, or physiological receptors. These analogs form a stable covalent bond at the binding site, thereby acting as inhibitors of the proteins or steroids. Affinity Labeling Reagents,Labeling Reagents, Affinity,Labels, Affinity,Reagents, Affinity Labeling
D001665 Binding Sites The parts of a macromolecule that directly participate in its specific combination with another molecule. Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining

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