Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.3.14 (ATP synthase)
 7,042 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aziridinium of purified quinacrine mustard at 50 microM inactivates the bovine heart mitochondrial F1-ATPase with a pseudo-first order rate constant of 0.07 min-1 at pH 7.0 and 23 degrees C. An apparent Kd of 27 microM for the enzyme-reagent complex was estimated from the dependence of the rate of inactivation on the concentration of quinacrine mustard. The pH inactivation profile revealed that deprotonation of a group with a pKa of about 6.7 is necessary for inactivation. The amount of reagent incorporated into the protein increased linearly with the extent of inactivation. Complete inactivation was estimated to occur when 3 mol of reagent were incorporated/mol of F1. Enzyme, in which steady state ATPase was inactivated by 98% by quinacrine mustard, hydrolyzed substoichiometric ATP with zero order kinetics suggesting that residual activity is catalyzed by F1 in which at least one beta subunit is modified. By exploiting the reactivity of the aziridinium of covalently attached reagent with [3H] aniline, sites modified by quinacrine mustard were labeled with 3H. Isolation of radioactive cyanogen bromide peptides derived from F1 inactivated with the reagent in the presence of [3H]aniline which were identified by sequence analysis and sequence analyses of radioactive tryptic fragments arising from them have revealed the following. About two thirds of the radioactivity incorporated into the enzyme during inactivation is apparently esterified to one or more of the carboxylic acid side chains in a CNBr-tryptic fragment of the beta subunit with the sequence: 394DELSEEDK401. The remainder of the radioactivity is associated with at least two sites within the cyanogen bromide peptide containing residues 293-358 of the beta subunit. From these results it is concluded that inactivation of F1 by the aziridinium of quinacrine mustard is due, at least in part, to modification of one or more of the carboxylic acid side chains in the DELSEED segment of the beta subunit and possibly also to modification of unspecified amino acid side chains between residues 302-356 of the beta subunit.
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PMID:Localization of sites modified during inactivation of the bovine heart mitochondrial F1-ATPase by quinacrine mustard using [3H]aniline as a probe. 252 84

The inactivation of the bovine heart mitochondrial F1-ATPase with 1-(ethoxycarbonyl)-2-ethoxy-1,2-dihydroquinoline (EEDQ) in the presence of [3H]aniline at pH 7.0 led to the covalent incorporation of 3H into the enzyme. When the ATPase was inactivated by 94% with 0.9 mM EEDQ in the presence of 3.6 mM [3H]aniline in a large-scale experiment in which the protein concentration was 21 mg/ml, 4.2 mol [3H]anilide were formed per mol enzyme, of which 0.35 mol was incorporated per mol of the alpha subunit and 1.0 mol was incorporated per mol of the beta subunit. Examination of a tryptic digest of the isolated alpha subunit revealed that the majority of the 3H was contained in a single tryptic peptide, which, when purified, was shown to contain the [3H]anilide of a glutamic acid residue which corresponds to alpha-Glu-402 of the Escherichia coli F1-ATPase. This residue was labeled to the extent of about 1.0 mol/mol enzyme. Analysis of tryptic peptides purified from the isolated beta subunit showed that 0.8 and 1.5 mol, respectively, of the [3H]anilides of beta-Glu-341 and beta-Glu-199 were formed per mol MF1 during the inactivation of the enzyme at 21 mg/ml. When the ATPase was inactivated by 90% at a protein concentration of 1.7 mg/ml by 0.9 mM EEDQ in the presence of 1.7 mM [3H]aniline, 3.1 mol [3H]anilide were formed per mol enzyme. From the analysis of the radioactive peptides purified from a tryptic digest of the labeled ATPase from this experiment it was estimated that 0.7 mol of the [3H]anilide of alpha-Glu-402, 0.3 mol of the [3H]anilide of beta-Glu-341, and 1.5 mol of the [3H]anilide of beta-Glu-199 were formed per mol F1-ATPase. Since beta-Glu-199 is labeled to the same extent in the two experiments while alpha-Glu-402 and beta-Glu-341 were not, suggests that the modification of beta-Glu-199 is responsible for inactivation of the enzyme by EEDQ.
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PMID:The use of [3H]aniline to identify the essential carboxyl group in the bovine mitochondrial F1-ATPase that reacts with 1-(ethoxycarbonyl)-2-ethoxy-1,2-dihydroquinoline. 286 44

Chemical mitochondrial uncouplers are lipophilic weak acids that transport protons into the mitochondrial matrix via a pathway that is independent of ATP synthase, thereby uncoupling nutrient oxidation from ATP production. These uncouplers have potential for the treatment of diseases such as obesity, Parkinson's disease, and aging. We have previously identified a novel mitochondrial protonophore, named BAM15, which stimulates mitochondrial respiration across a broad dosing range compared to carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP). Herein, we report our investigations on the structure-activity relationship profile of BAM15. Our studies demonstrate the importance of the furazan, pyrazine, and aniline rings as well as pKa in maintaining its effective protonophore activity.
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PMID:Structure-activity relationships of furazano[3,4-b]pyrazines as mitochondrial uncouplers. 2611 1