Podcast
Questions and Answers
In allosteric enzymes, where do allosteric activators and inhibitors bind?
In allosteric enzymes, where do allosteric activators and inhibitors bind?
- Catalytic site
- Cooperative site
- Substrate site
- Allosteric site (correct)
What effect do allosteric effectors have on enzyme-substrate affinity?
What effect do allosteric effectors have on enzyme-substrate affinity?
- They decrease it
- They stabilize it
- They increase it (correct)
- They have no effect
How do allosteric enzymes usually exhibit substrate binding?
How do allosteric enzymes usually exhibit substrate binding?
- Positive cooperativity (correct)
- No cooperativity
- Competitive binding
- Negative cooperativity
In the 'T' conformation of allosteric enzymes, what is the affinity for substrate?
In the 'T' conformation of allosteric enzymes, what is the affinity for substrate?
What conformation does the first substrate molecule change to upon binding in allosteric enzymes?
What conformation does the first substrate molecule change to upon binding in allosteric enzymes?
What kind of fashion do allosteric enzymes generally change to the new conformation?
What kind of fashion do allosteric enzymes generally change to the new conformation?
What is the role of the rate-limiting step in metabolic pathways?
What is the role of the rate-limiting step in metabolic pathways?
What happens when the rate-limiting enzyme in a pathway is inhibited?
What happens when the rate-limiting enzyme in a pathway is inhibited?
How does feedback regulation usually involve the rate-limiting enzyme?
How does feedback regulation usually involve the rate-limiting enzyme?
What is feed-forward regulation associated with?
What is feed-forward regulation associated with?
Why do regulatory enzymes of pathways usually exist as tissue-specific isozymes?
Why do regulatory enzymes of pathways usually exist as tissue-specific isozymes?
What is the function of GK, the low-affinity enzyme found in the liver?
What is the function of GK, the low-affinity enzyme found in the liver?
Which type of enzymes exhibit sigmoidal velocity versus substrate concentration plots?
Which type of enzymes exhibit sigmoidal velocity versus substrate concentration plots?
What effect do allosteric activators have on enzyme activity?
What effect do allosteric activators have on enzyme activity?
Which molecules regulate rate-limiting enzymes in fuel oxidation pathways?
Which molecules regulate rate-limiting enzymes in fuel oxidation pathways?
What is the role of protein kinases in enzyme regulation?
What is the role of protein kinases in enzyme regulation?
How do allosteric effectors compare to competitive and noncompetitive inhibitors in terms of regulation?
How do allosteric effectors compare to competitive and noncompetitive inhibitors in terms of regulation?
What is the purpose of covalent modification in enzyme regulation?
What is the purpose of covalent modification in enzyme regulation?
Which process directly activates or inhibits enzymes?
Which process directly activates or inhibits enzymes?
What activates muscle glycogen phosphorylase kinase, aiding in ATP synthesis for muscle contraction?
What activates muscle glycogen phosphorylase kinase, aiding in ATP synthesis for muscle contraction?
What influences the activity of G-proteins by increasing GTP hydrolysis?
What influences the activity of G-proteins by increasing GTP hydrolysis?
What causes conformational changes to activate or inhibit the function of various proteins?
What causes conformational changes to activate or inhibit the function of various proteins?
What initiates a phosphorylation cascade by increasing cAMP levels?
What initiates a phosphorylation cascade by increasing cAMP levels?
What regulates various cellular functions through reversible protein association?
What regulates various cellular functions through reversible protein association?
Which family is NOT part of the Ras superfamily of small G-proteins?
Which family is NOT part of the Ras superfamily of small G-proteins?
What prevents premature cleavage of proteins at their sites of synthesis or secretion?
What prevents premature cleavage of proteins at their sites of synthesis or secretion?
What process involves the regulation of gene transcription, translation, and messenger RNA stabilization?
What process involves the regulation of gene transcription, translation, and messenger RNA stabilization?
Which enzyme's maximal capacity in the liver is increased with continued ingestion of ethanol through induction of gene transcription?
Which enzyme's maximal capacity in the liver is increased with continued ingestion of ethanol through induction of gene transcription?
What are metabolic pathways?
What are metabolic pathways?
What may a metabolic pathway have at which an intermediate becomes the precursor for another pathway?
What may a metabolic pathway have at which an intermediate becomes the precursor for another pathway?
Study Notes
Regulation of Enzyme Activity and Metabolic Pathways
- The Ras superfamily of small G-proteins is divided into five families: Ras, Rho, Arf, Rab, and Ran.
- These monomeric G-proteins are bound to a lipid membrane through a lipid anchor and regulate the assembly and activity of protein complexes at these sites.
- Proteolytic cleavage is irreversible and involves zymogens, precursor proteins that must undergo proteolytic cleavage to become fully functional enzymes.
- Zymogens prevent premature cleavage of proteins at their sites of synthesis or secretion.
- Enzymes involved in blood clotting, such as fibrinogen and prothrombin, are zymogens that are cleaved to the active form by other proteases.
- Tissues adjust the rate of protein synthesis to vary the amount of different enzymes present.
- Regulation of enzyme synthesis occurs through gene transcription, translation, and messenger RNA stabilization, which can be induced or repressed.
- Protein degradation can be selectively regulated, as seen in skeletal muscle during fasting or infective stress.
- The regulation of enzyme activity controls metabolic pathways and physiologic processes to match the body’s requirements.
- The maximal capacity of MEOS (cytochrome P450-2E1) in the liver is increased with continued ingestion of ethanol through induction of gene transcription.
- Metabolic pathways are a series of sequential reactions catalyzed by separate enzymes, with a common function of converting substrates to end products.
- Each step in a pathway is usually catalyzed by a separate enzyme, and a pathway may have a branch point at which an intermediate becomes the precursor for another pathway.
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Description
Test your knowledge of enzyme activity regulation and metabolic pathways with this quiz. Explore topics such as zymogens, gene transcription, protein degradation, and the role of small G-proteins in regulating enzyme activity.
