What class of enzyme is aconitase?
Enzyme
Aconitase/Classification
What is the product of the enzyme aconitase?
The enzyme aconitase is a key player in the central pathway of energy production. As part of the citric acid cycle, it converts citrate into isocitrate. The animation shows histidine acting as an acid protonates the hydroxyl on the substrate, allowing it to leave as a water molecule.
What is mitochondrial aconitase?
Mitochondrial aconitase is a reversible enzyme that catalyzes the conversion of citrate to isocitrate in the tricarboxylic acid cycle. Mitochondrial aconitase is very sensitive to oxidative inactivation and can aggregate and accumulate in the mitochondrial matrix causing mitochondrial dysfunction.
Which enzyme is functionally similar to aconitase?
The iron-responsive element-binding protein (IRE-BP) and 3-isopropylmalate dehydratase (α-isopropylmalate isomerase; EC 4.2. 1.33), an enzyme catalysing the second step in the biosynthesis of leucine, are known aconitase homologues.
What cofactor is present in aconitase?
Catalytic mechanism of mitochondrial ACO The (4Fe-4S) cofactor is held in place by three sulfur atoms belonging to the cysteins-385, -448, and -451 which are bound to three of the four cluster iron atoms. On activation of the enzyme, a fourth iron atom is included in the cluster together with a water molecule.
What type of protein is aconitase?
monomer globular protein
Aconitase is a monomer globular protein. Inactive aconitase has a [3Fe-4S] cluster at its active site, while active aconitase has a [4Fe-4S] cluster. The protein consists of 754 amino acids, with a total molecular weight of 82693.1 Da and a theoretical isoelectric point of 7.2 (3).
Where is aconitase used?
There is one form of aconitase in our mitochondria, which performs most of the conversion for the citric acid cycle, and a similar form in the cytoplasm that creates isocitrate for other synthetic tasks.
What are the cofactors of aconitase?
Aconitase requires an iron-sulfur cluster cofactor which binds Fe2+ to activate the enzyme. The iron in this position binds to the C-3 carboxyl and hydroxyl groups of the substrate citrate and acts as a Lewis acid to make the hydroxyl a better leaving group.
Is aconitase reversible?
Aconitases are iron-sulfur proteins which catalyze the reversible isomerization of citrate and isocitrate via cis-aconitate.
How does an increased level of zinc affect the function of aconitase?
The much higher endogenous level of zinc does inhibit the m-aconitase activity of prostate mitochondria; therefore, the reduction of zinc concentrations by EDTA treatment results in increased m-aconitase activity.
How is aconitase regulated?
Aconitase is one such enzyme. Some of these enzymes are tightly regulated, either activated or inhibited, by the concentration of reactant, product, ATP or NADH, and thus are rate-determining. Both Citrate synthase and Isocitrate dehydogenase are inhibited by NADH concentration, but aconitase itself is not.
What is aconitase reaction?
Aconitase performs a reaction in the citric acid cycle, and moonlights as a regulatory protein. Aconitase (top) and the same protein acting as an iron regulatory protein bound to part of a messenger RNA.
How is the aconitase activity of a cell measured?
The aconitase activity of cell lysates can be measured spectrophotometrically by monitoring the formation of cis -aconitate from isocitrate at 240 nm in 50 m M Tris–HCl (pH 7.4) containing 0.6 m M MnCl 2 and 20 m M isocitrate ( Krebs & Holzach, 1952; Patel et al., 1996 ). Method II.
What is the role of aconitase in the tricarboxylic cycle?
Aconitases are enzymes that catalyze the stereospecific isomerization of citrate to isocitrate in the tricarboxylic cycle [1 ]. They are iron–sulfur proteins that contain [4Fe—4S] clusters.
What is the structure of the enzyme aconitate hydratase?
Structure of aconitase. Aconitase (aconitate hydratase; EC 4.2.1.3) is an enzyme that catalyses the stereo-specific isomerization of citrate to isocitrate via cis – aconitate in the tricarboxylic acid cycle, a non- redox -active process.
Is the iron-sulfur cluster of aconitase active?
In contrast with the majority of iron-sulfur proteins that function as electron carriers, the iron-sulfur cluster of aconitase reacts directly with an enzyme substrate. Aconitase has an active [Fe 4 S 4] 2+ cluster, which may convert to an inactive [Fe 3 S 4] + form.