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Does the allosteric effect in an enzyme change the enzyme's function?
Yes, the allosteric effect can change an enzyme's function by altering its activity or affinity for its substrate. This modulation is often achieved by a molecule binding to a site on the enzyme other than the active site, causing a conformational change that affects the enzyme's catalytic activity.
What is an enzyme called when it changes shape?
An enzyme is called a denatured enzyme once it changes its shape.
Why allosteric enzymes do not obey michealis menten kinetics?
Allosteric enzymes do not obey Michaelis-Menten kinetics because their activity is regulated by the binding of effector molecules at sites other than the active site, leading to a conformational change in the enzyme. This results in a sigmoidal (S-shaped) reaction rate curve rather than the hyperbolic curve typical of Michaelis-Menten kinetics. Additionally, allosteric enzymes often exhibit cooperative binding, meaning the binding of substrate to one active site affects the binding properties of other sites, further deviating from the assumptions of Michaelis-Menten kinetics.
Is p-nitrophenol an enzyme?
No, p-nitrophenol is not an enzyme. It is a chemical compound that is often used in biochemical research as a substrate for enzyme assays.
What is a co enzyme used for?
A coenzyme is a molecule that helps enzymes to carry out their functions in the body. Coenzymes often act as carriers of electrons or small functional groups during chemical reactions. Examples include NAD+ and FAD which are involved in energy production processes like cellular respiration.
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 is the expectation for enzymes concentration?
The expectation for enzyme concentration typically depends on the specific reaction and conditions in which the enzyme is functioning. Generally, enzyme concentration is expected to be sufficient to catalyze reactions at a desired rate without becoming a limiting factor. In many biological systems, enzyme concentrations can vary widely, often being regulated to ensure metabolic efficiency. Optimal concentrations are usually determined experimentally based on the specific requirements of the biochemical pathways involved.
What does the name of an enzyme tell us?
The name of an enzyme typically indicates its substrate or the type of reaction it catalyzes. Enzyme names often end in "-ase" to show that it is an enzyme. Additionally, the name may provide information about the enzyme's source or origin, such as "pepsin" from the stomach.
What kind of chemical reactions speed up enzyme catalysis?
This varies per enzyme and what it catalyzes but chemical reactions that result in an increase in temperature often speed up enzyme catalysis.
What kind of mechanism is the enzyme-subtrate complex often compared to?
The enzyme-substrate complex is often compared to a lock-and-key mechanism. In this analogy, the enzyme acts as the lock, and the substrate is the key that fits perfectly into the enzyme's active site. This specificity ensures that only particular substrates can bind to the enzyme, facilitating the biochemical reaction. Alternatively, the induced fit model also describes this interaction, suggesting that the enzyme can change shape to better accommodate the substrate upon binding.
What do you call the rate of an enzyme catalyzed reaction?
The rate of an enzyme-catalyzed reaction is often referred to as the enzyme's catalytic activity or turnover rate. It is a measure of how quickly the enzyme can convert substrate molecules into products.
How do competitive and noncompetitive inhibitions differ?
A competitive inhibitor often binds to an enzyme's active site. Noncompetitive inhibitors usually bind to a different site on the enzyme.
