How is aconitase regulated?
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. Isocitrate dehydrogenase uses the product of the reaction aconitase catalyzes.
What is the purpose of the aconitase reaction in the TCA cycle?
Mitochondrial aconitase converts citrate to isocitrate in the tricarboxylic acid cycle (TCA) and serves as a TCA cycle regulatory enzyme sensitive to oxidation.
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).
What is the function of aconitase How is it inhibited?
Aconitase is inhibited by fluoroacetate, therefore fluoroacetate is poisonous. Fluoroacetate, in the citric acid cycle, can innocently enter as fluorocitrate. However, aconitase cannot bind this substrate and thus the citric acid cycle is halted. The iron sulfur cluster is highly sensitive to oxidation by superoxide.
What happens when the protein aconitase binds to iron?
When the iron regulatory protein 1 binds, it inhibits the formation of ferritin, so that less iron is locked up in storage, and it enhances construction of the transferrin receptor, so the cell can pick up more transferrin out of the blood, and with it, more iron.
Is aconitase a isomerase?
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 is the function of iron regulatory proteins?
Iron regulatory proteins (IRPs) regulate the expression of genes involved in iron metabolism by binding to RNA stem-loop structures known as iron responsive elements (IREs) in target mRNAs.
Where are iron regulatory proteins found?
Two iron-regulatory proteins (IRP1, coded on chromosome 9, and IRP2, coded on chromosome 15), are able to bind to sequences which form stem loop structures called iron responsive elements (IREs) in the untranslated regions of mRNAs for transferrin receptor and both H- and L-subunits of ferritin (Fig. 11.3).