Esterase activity of high-Km aldehyde dehydrogenase from rat liver mitochondria

1990 ◽  
Vol 68 (4) ◽  
pp. 758-763 ◽  
Author(s):  
Dave J. Senior ◽  
C. Stan Tsai
Keyword(s):  
Rat Liver ◽  
Aldehyde Dehydrogenase ◽  
Esterase Activity ◽  
Binding Capacity ◽  
Kinetic Studies ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Electronic Effects ◽  
Steady State Kinetic ◽  
Esterolytic Activity

Aldehyde dehydrogenase possessing an esterolytic activity has been purified to homogeneity from rat liver mitochondria. Steady-state kinetic studies suggest that the esterolytic reaction follows an ordered uni-bi mechanism. The formation of an acyl enzyme intermediate via nucleophilic catalysis during the esterase reaction is established kinetically using a series of substrates with varying acyl carbon chains and substituted phenyl octanoates with varying electronic effects. The enzyme was reconstituted into phospholipid vesicles. A significant increase in binding capacity is observed when the enzyme is encapsulated into liposomes containing 4% diphosphatidylglycerol.Key words: aldehyde dehydrogenase, esterase activity.

Chemical studies of high-Km aldehyde dehydrogenase from rat liver mitochondria

1991 ◽  
Vol 69 (2-3) ◽  
pp. 193-197 ◽  
Author(s):  
C. Stan Tsai ◽  
David J. Senior
Keyword(s):  
Dehydrogenase Activity ◽  
Rat Liver ◽  
Aldehyde Dehydrogenase ◽  
Esterase Activity ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Coenzyme Binding ◽  
High K ◽  
Chemical Studies ◽  
Ionizable Groups

Studies of pH-dependent kinetics implicate two ionizable groups in the dehydrogenase and esterase reactions catalysed by high-Km aldehyde dehydrogenase from rat liver mitochondria. Sensitized photooxidation completely arrests the bifunctional activities of the dehydrogenase. Carboxamidomethylation abolishes the dehydrogenase activity, whereas acetimidination eliminates the esterase activity. These results suggest that histidine (pKa near 6) and cysteine (pKa near 10) are likely the catalytic residues for the dehydrogenase activity, while the esterase activity is functionally related to histidine (pKa near 7) and a residue with the pKa value of 10–11. The two residues, a carboxyl group and an arginine, that discriminate between NAD+ and NADP+ are present at the coenzyme binding site of the mitochondrial high-Km aldehyde dehydrogenase from rat liver.Key words: aldehyde dehydrogenase, rat liver, mitochondria, esterase.

Characterization of the binding of 3,3′-di-iodo-l-thyronine to rat liver mitochondria

1997 ◽  
Vol 154 (1) ◽  
pp. 119-124
Author(s):  
A Lombardi ◽  
M Moreno ◽  
C Horst ◽  
F Goglia ◽  
A Lanni
Keyword(s):  
Rat Liver ◽  
Binding Capacity ◽  
Specific Binding ◽  
Local Environment ◽  
Liver Mitochondria ◽  
Ion Concentration ◽  
Affinity Constant ◽  
Rat Liver Mitochondria ◽  
Inner Mitochondrial Membrane ◽  
Thyroid State

Abstract The binding of labelled 3,3′-di-iodo-l-thyronine (3,3′-T2) to isolated rat liver mitochondria has been characterized. Specific binding could be detected only in the inner mitochondrial membrane, not in other mitochondrial subfractions. The composition of the incubation medium influenced the binding capacity, the best combination of high specific binding and low non-specific binding being observed in phosphate buffer, pH 6·4. The specific binding of 3,3′-T2 to mitochondria requires low ionic strength: concentrations of K+ and Na+ higher than 10 mmol/l and 0·1 mmol/l respectively resulted in a decreased binding capacity. The optimal calcium ion concentration was in the range 0·01–1·0 mmol/l. Varying magnesium ion, over the range of concentrations used (0·1–100 mmol/l), had no effect. Both ADP and ATP, at over 1 mmol/l, resulted in an inhibition of the specific binding. Incubation with protease resulted in a decrease in specific binding and an increase in non-specific binding, thus indicating the proteic nature of the binding sites. In addition to the above factors in the local environment the thyroid state of the animal might influence the 3,3′-T2-binding capacity. In fact, the thyroid state of the animal seemed not to have an influence on the affinity constant, but it did affect binding capacity. Journal of Endocrinology (1997) 154, 119–124

scholarly journals The control of isocitrate oxidation by rat liver mitochondria

1969 ◽  
Vol 114 (2) ◽  
pp. 215-225 ◽  
Author(s):  
D. G. Nicholls ◽  
P. B. Garland
Keyword(s):  
Respiratory Chain ◽  
Rat Liver ◽  
Isocitrate Dehydrogenase ◽  
Adenine Nucleotides ◽  
Kinetic Studies ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Kinetic Properties ◽  
Dependent Inhibition ◽  
Nad 4

1. The factors capable of affecting the rate of isocitrate oxidation in intact mitochondria include the rate of isocitrate penetration, the activity of the NAD-specific and NADP-specific isocitrate dehydrogenases, the activity of the transhydrogenase acting from NADPH to NAD+, the rate of NADPH oxidation by the reductive synthesis of glutamate and the activity of the respiratory chain. A quantitative assessment of these factors was made in intact mitochondria. 2. The kinetic properties of the NAD-specific and NADP-specific isocitrate dehydrogenases extracted from rat liver mitochondria were examined. 3. The rate of isocitrate oxidation through the respiratory chain in mitochondria with coupled phosphorylation is approximately equal to the maximal of the NAD-specific isocitrate dehydrogenase but at least ten times as great as the transhydrogenase activity from NADPH to NAD+. 4. It is concluded that the energy-dependent inhibition of isocitrate oxidation by palmitoylcarnitine oxidation is due to an inhibition of the NAD-specific isocitrate dehydrogenase. 5. Kinetic studies of NAD-specific isocitrate dehydrogenase demonstrated that its activity could be inhibited by one or more of the following: an increased reduction of mitochondrial NAD, an increased phosphorylation of mitochondrial adenine nucleotides or a fall in the mitochondrial isocitrate concentration. 6. Uncoupling agents stimulate isocitrate oxidation by an extent equal to the associated stimulation of transhydrogenation from NADPH to NAD+. 7. A technique is described for continuously measuring with a carbon dioxide electrode the synthesis of glutamate from isocitrate and ammonia.

Dual coenzyme activities of high-Km aldehyde dehydrogenase from rat liver mitochondria

1990 ◽  
Vol 68 (4) ◽  
pp. 751-757 ◽  
Author(s):  
C. Stan Tsai ◽  
D. J. Senior
Keyword(s):  
Steady State ◽  
Rat Liver ◽  
Aldehyde Dehydrogenase ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Binary Complex ◽  
Stopped Flow ◽  
Conformation Change ◽  
Rate Limiting ◽  
Flow Burst

Various kinetic approaches were carried out to investigate kinetic attributes for the dual coenzyme activities of mitochondrial aldehyde dehydrogenase from rat liver. The enzyme catalyses NAD+- and NADP+-dependent oxidations of ethanal by an ordered bi-bi mechanism with NAD(P)+ as the first reactant bound and NAD(P)H as the last product released. The two coenzymes presumably interact with the kinetically identical site. NAD+ forms the dynamic binary complex with the enzyme, while the enzyme-NAD(P)H complex formation is associated with conformation change(s). A stopped-flow burst of NAD(P)H formation, followed by a slower steady-state turnover, suggests that either the deacylation or the release of NAD(P)H is rate limiting. Although NADP+ is reduced by a faster burst rate, NAD+ is slightly favored as the coenzyme by virtue of its marginally faster turnover rate.Key words: aldehyde dehydrogenase, coenzyme preference.

Metabolism of nitroglycerin by rat liver mitochondria and purified mitochondrial aldehyde dehydrogenase

2003 ◽  
Vol 3 (S2) ◽  
Author(s):  
Alexandra Hofer ◽  
Alexander Kollau ◽  
Wing Ming Keung ◽  
Kurt Schmidt ◽  
Bernd Mayer
Keyword(s):  
Rat Liver ◽  
Aldehyde Dehydrogenase ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria

Inactivation of aldehyde dehydrogenase in intact rat liver mitochondria by dopamine

Alcohol ◽  
1989 ◽  
Vol 6 (6) ◽  
pp. 455-460 ◽  
Author(s):  
Saffiya Catovic Turan ◽  
Pritesh Shah ◽  
Regina Pietruszko
Keyword(s):  
Rat Liver ◽  
Aldehyde Dehydrogenase ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria
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