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Which one of the following would you predict is an allosteric inhibitor of the Krebs cycle enzyme ketoglutarate dehydrogenase?
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∙ 13y ago
NADH
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What blocks enzyme activity by binding to allosteric site of an enzyme causing the enzyme's active site to change shape?
An allosteric inhibitor stops enzyme activity by binding to an allosteric site and causing the conformation of the enzyme to change.
Does Allosteric regulation depends on inhibitors binding to the active site of enzymes?
Of course. That is the meaning of ' noncompetitive inhibitor. ' It does not compete with the substrate at the active site but inhibits enzyme activity at the allosteric ( other site ) site.
How do allosteric regulation and competitive inhibition compare?
A competitive inhibition and allosteric regulation both involves an inhibitor molecule binding to the enzyme at a different area. The difference between the two is that allosteric inhibitors are modulator molecules which bind somewhere besides the catalytic activity.
What is non allosteric enzymes?
A second and reversible form of regulation is known as allosteric regulation In allosteric regulation, regulatory molecules bind reversibly to the protein, altering its confirmation, which in turn alters its activity. Such allosteric effectors are not covalently attached to the protein. Here, the activity of a protein is positively regulated by the binding of a factor. This factor could be a small molecule or another protein. What is important is that the allosteric binding site is distinct from the enzyme's catalytic site. That is what allosteric means, other site. An allosteric effector can also act negatively, inhibiting enzyme activity. Because allosteric regulators do not bind to the same site on the protein as the substrate, changing substrate concentration generally does not alter their effects. Of course there are other types of regulation as well. Active site inhibitors: An inhibitory factor may bind to and block the active site. If this binding is reversible, then increasing the amount of substrate can over-come the inhibition. An inhibitor of this type is known as a competitive inhibitor. In some cases, the inhibitor chemically reacts with the enzyme, forming a covalent bond. Because this type of inhibitor is essentially irreversible, increasing substrate concentration can not overcome inhibition. These are therefore known as a noncompetitive inhibitors. Biofundamentals - Regulating protein activity 9/27/08 11:13 AM file:///Users/klymkowsky/Documents/WebSites/virtual/Biofundamentals/lectureNotes/Topic3-6_Protein%20Activity.htm Page 3 of 6 Allosteric effectors are also non-competitive, since they do not compete with substrate for binding to the active site. A protein binds an allosteric regulator - what happens to the protein? Why are allosteric regulators not "competitive"? What makes an inhibitor that binds to the active site of an enzyme "non-competitive" ? Post-translational regulation: Proteins may be modified after synthesis - this process is known as post-translational modification. A number of posttranslational modifications have been found to occur within cells. The first type involve the covalent addition of specific groups to the protein - these groups can range from phosphate groups (phosphorylation), an acetate group (acetylation), the attachment of lipid/hydrophobic groups (lipid modification), or carbohydrates (glycosylation) . Often post-translational modifications are reversible, one enzyme adds the modifying group, and another can act to remove it. For example, proteins are phosphorylated by enzymes known as protein kinases, while protein phosphatases remove phosphate groups. Post-translational modifications act in much the same way as do allosteric effectors, they modify the activity of the polypeptide to which they are attached. They can also modify a proteins interactions with other proteins, the protein's localization within the cell, or its stability. Proteolytic processing: Another method for regulating protein activity involves the cleavage of the polypeptide chain. Many proteins are originally synthesized in a longer, and inactive "pro-form". To become active the propeptide must be removed - it is cut by a protease. This proteolytic processing activates the protein. Proteolytic processing is itself often regulated. A protein is normally found free in the cytoplasm; where would you expect it would be found following addition of a lipid group? What are the advantages/disadvantages of using proteolytic activation, compared to allosteric activation of a protein? Biofundamentals - Regulating protein activity 9/27/08 11:13 AM file:///Users/klymkowsky/Documents/WebSites/virtual/Biofundamentals/lectureNotes/Topic3-6_Protein%20Activity.htm Page 4 of 6 activation, compared to allosteric activation of a protein? Why are enzymes required for post-translational modification? Do you think post-translational modification requires energy? Telling proteins where to go: Translation of proteins occurs in the cytoplasm, where mature ribosomes are located. If no information is added, a newly synthesized polypeptide will remain in the cytoplasm, that is its default location. Yet even in the structurally simplest of cells, the prokaryotes (bacteria and archaea), there is more than one place that a protein may end up: it can remain in the cytoplasm, it can be inserted in the plasma membrane or it may be secreted from the cell. Both membrane and secreted polypeptides must be inserted into, or pass through, the plasma membrane. Polypeptides destined for the membrane or for secretion are generally marked by a specific tag, known as a signal sequence. The signal sequence consists of a stretch of hydrophobic amino acids, often at the N-terminus of the polypeptide. As the signal sequence emerges from the ribosome it interacts with a signal recognition particle or SRP - a complex of polypeptides and a structural RNA. The binding of SRP to the signal sequence causes translation to pause. The mRNA/ribosome/nascent polypeptide/SRP complex will find (by diffusion), and attach to, a ribosome/SRP receptor complex on the cytoplasmic surface of the plasma membrane. This ribosome/SRP receptor is associated with a polypeptide pore. When the ribosome/SRP complex docks with the receptor, translation resumes and the nascent polypeptide passes through a protein pore and so through the membrane. As the polypeptide emerges on the extracytoplasmic side of the membrane, the signal sequence is generally removed by an enzyme, signal sequence peptidase. If the polypeptide is a membrane protein, it will remain within the membrane. If it is a secreted polypeptide, it will be released into the periplasmic space. _armanfiroz_
What does a repressor do in the enzymes active site?
Repressors bind to the silencers in the DNA to block the RNA polymerase from binding to the promoter of the gene to reduce gene expression, not really binding to enzymes active sites I think what you meant was "what does an inhibitor do to the enzymes active site"? In which case, it depends on the type of inhibitor. A competitive inhibitor has a structure similar to the substrate, hence would bind to the active site as well, competing with the substrate for the enzyme active sites, decreasing enzymatic activity. A non-competitive inhibitor binds to the allosteric site of the enzyme, causing a structural change in the enzyme active site shape. Hence the enzyme would not be able to bind to the original substrate, so enzymatic activity comes to a halt for the enzymes that are bound by the non-competitive inhibitors
What is allosteric inhibitor of glutamate dehydrogenase?
GTP
What is the allosteric inhibitor?
The inhibitor which binds or attached with the allosteric site of enzyme k/n as A.I ... BY "NAHEED KHATTI "
What is Malonic acids role with respect to succinate dehydrogenase?
Malonic acid is a competitive inhibitor of succinate dehydrogenase.
Why is mitochondrial respiration dependent on ADP?
Isocitrate Dehydrogenase transforms isocitrate into alpha-ketoglutarate and is an important step in the citric acid cycle. This enzyme utilises NAD+ as a co-enzyme, NAD+ also acts as an allosteric inhibitor increasing the enzymes affinity for substrates. High ADP, High turn over of this enzyme meaning more citric acid cyle. Which in turn results in the high energy carriers that are donate electrons to the electron transport chain involved in pumping protons in the mitochondria. Also Pyruvate dehydrogenase (pyruvate --> acety CoA) is an irreversible step which links glycolosis to the citric acid cycle, this too has its activity increased by ADP
What blocks enzyme activity by binding to allosteric site of an enzyme causing the enzyme's active site to change shape?
An allosteric inhibitor stops enzyme activity by binding to an allosteric site and causing the conformation of the enzyme to change.
What is an inhibitor that forms a covalent bond with an amino acid side group within the active site?
Competitive inhibitor source - AP Bio Text Book
Does Allosteric regulation depends on inhibitors binding to the active site of enzymes?
Of course. That is the meaning of ' noncompetitive inhibitor. ' It does not compete with the substrate at the active site but inhibits enzyme activity at the allosteric ( other site ) site.
Why does adding additional substrate overcome competitive but not noncompetitive inhibition?
A competitive inhibitor competes with the substrate to bind to the active site while a noncompetitive inhibitor binds to an allosteric site of the enzyme (one other than the active site). Thus no amount of substrate can overcome or in a sense interfere with the inhibitors binding to an allosteric site.
How malonate inhibit the conversion of succinate to fumarate?
Malonate is a competitive inhibitor of succinate dehydrogenase, the enzyme responsible for converting succinate to fumarate in the citric acid cycle. Malonate resembles succinate and competes for the active site of succinate dehydrogenase. As a result, malonate binds to the enzyme and prevents succinate from binding, inhibiting the conversion of succinate to fumarate.
What happens during allosteric inhibition?
Allosteric (noncompetitive) inhibition results from a change in the shape of the active site when an inhibitor binds to an allosteric site. When this occurs the substrate cannot bind to its active site due to the fact that the active site has changed shape and the substrate no longer fits. Allosteric activation results when the binding of an activator molecule to an allosteric site causes a change in the active site that makes it capable of binding substrate.
How do allosteric regulation and competitive inhibition compare?
A competitive inhibition and allosteric regulation both involves an inhibitor molecule binding to the enzyme at a different area. The difference between the two is that allosteric inhibitors are modulator molecules which bind somewhere besides the catalytic activity.
How does ethanol prevent ethylene glycol poisoning?
Ethanol serves as a competitive inhibitor which competes with glycol for the enzyme alcohol dehydrogenase's active site. Thus, less glycol will be oxidised
