Concept explainers
(a)
Interpretation:
The effect in the rate of an enzyme-catalysed reaction if the substrate concentration at a constant inhibitor concentration is increased should be determined.
Concept Introduction:
Enzyme:
- It is a protein or a molecule which can act as a catalyst for a biological reaction.
- Does not affect the equilibrium point of the reaction.
- Active site of the enzyme is the region where the reaction takes place.
- Enzyme’s activity can be specific which means the activity is limited to a certain substrate and a certain type of reaction and it is referred to as specificity of the enzyme.
Enzyme inhibitors: The substance which slows or stops the action of an enzyme is called enzyme inhibitors.
It can be used as drugs and an example is AZT which is used to treat HIV.
The competition of an enzyme can be reversible or irreversible and in reversible inhibition, the inhibitor can leave and in irreversible inhibition, the inhibitor remains permanently bound.
(b)
Interpretation:
The effect in the rate of an enzyme-catalysed reaction if the inhibitor concentration at a constant substrate concentration is decreased should be determined.
Concept Introduction:
Enzyme:
- It is a protein or a molecule which can act as a catalyst for a biological reaction.
- Does not affect the equilibrium point of the reaction.
- Active site of the enzyme is the region where the reaction takes place.
- Enzyme’s activity can be specific which means the activity is limited to a certain substrate and a certain type of reaction and it is referred to as specificity of the enzyme.
Enzyme inhibitors: The substance which slows or stops the action of an enzyme is called enzyme inhibitors.
It can be used as drugs and an example is AZT which is used to treat HIV.
The competition of an enzyme can be reversible or irreversible and in reversible inhibition, the inhibitor can leave and in irreversible inhibition, the inhibitor remains permanently bound.
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Check out a sample textbook solutionChapter 19 Solutions
Fundamentals of General, Organic, and Biological Chemistry (8th Edition)
- For the following two scenarios, sketch the complete reaction free energy diagram for an enzyme-catalyzed conversion of a single substrate (S) into product (P), where the reaction is spontaneous in the forward direction. For each of these, overlay the free energy diagram for the uncatalyzed reaction and indicate AAG" on your sketch: a). Substrate binding is rate limiting b). The chemical step is rate limitingarrow_forwardb) Enzymes accelerate reactions by facilitating the formation of the transition state. Define transition state and activation energy. For full credit, you need to present the actual graph (for an endergonic or exergonic reaction - make sure to specify your choice) highlighting each term? c) Explain how an irreversible inhibitor for an enzymatic reaction differs from reversible inhibitors. Provide specific example of an irreversible inhibitor and its target enzyme d) Determine the Vo as a function of Vmax when the substrate concentration is equal to 10 KM or 20 KM. What does this tell you about an enzyme ability to reach Vmax?arrow_forwardHow does the Michaelis-Menten equation explain why the rate of an enzyme-catalyzed reaction reaches a maximum value at high substrate?arrow_forward
- All of the following statements about competitive and non-competitive inhibitors are true EXCEPT:(a) Competitive inhibitors are structurally similar to anenzyme’s substrate and bind to the enzyme’s allostericsite.(b) Competitive inhibitors work by competing with a sub-strate for binding to an enzyme’s active site.(c) Noncompetitive inhibitors can bind at sites other thanthe active site of an enzyme, distorting the tertiary pro-tein structure, which alters the shape of the active site,rendering it ineffective for substrate binding.(d) Some noncompetitive inhibitors bind reversibly whilesome bind irreversibly to their enzyme.(e) b and d.arrow_forwardUnder the following conditions, fill in the blanks. Then, describe why this inhibitor is the type of inhibitor you identified it as. If you were to add 5nM of a reversible inhibitor, the Km for the measured enzyme catalyzed reaction would ______ (Increase, Decrease, Stay the same) to ______µM (choose appropriate value) and Vmax would _______ (Increase, Decrease, Stay the same) to ______µMs-1. So, this inhibitor is a ______ (Competitive, Uncompetitive, Mixed) inhibitor. Conditions: kcat = 130 s^-1 Vo = 3.0 μMs-1 S = 10 μM Et = 0.09 µMarrow_forwardWhich of the following is true under the following conditions: an enzyme displaying Michaelis-Menten kinetics where the enzyme concentration is 10 nM, the substrate concentration is 45 mM, and the Km is 50 µM? a) The enzyme has low catalytic efficiency for the substrate. b)The rate of catalysis is near half-maximal velocity. c)The enzymatic reaction is near maximal velocity. d)Halving the substrate concentration has little effect on the catalytic rate. e) There is not enough information provided.arrow_forward
- a) Based on the data shown in the image, what are the Km and Vmax for the enzyme with L-DOPA and D-DOPA? Show any relevant analyses or calculatins you did to determine these values. ( HINT a graph might be helpful here! ) b) Based on your answer to part a, briefly describe how the kinetics of the enzyme differs for the two substrates. Which Substrate has better binding affinity to the enzymearrow_forwardRegarding the physical condition (characteristics of the solution/environment) in which an enzyme finds itself: sometimes enzymes are most active at a certain level and still active but to a lesser degree at a level above or below the optimal level. Describe the likely reason for the enzyme’s decrement in function at levels other than the optimal level?arrow_forwardIn the scheme for enzymatic catalysed reaction proposed by Michaelis and Menten, the steps involve reversible formation of enzyme-substrate (ES) complex followed by conversion of the complex to the product (P). a) Derive the rate equation for enzymatic process. State an assumption made in this derivation. Terbitkan persamaan kadar tindak balas bagi proses enzim. b) By showing appropriate reaction mechanisms and rate equations, explain how enzyme catalytic reactions may be affected by competitive inhibitionarrow_forward
- List down the properties of an ideal carrier matrix for enzyme immobilization.arrow_forwardOne of the hallmarks of competitive inhibition is that there is constant competition betweenthe substrate and the inhibitor for binding to the enzyme active site.a) If [inhibitor] >> [substrate], which compound “wins” (i.e., occupies the active site a greaterpercentage of the time)?b) If [substrate] >> [inhibitor], which compound “wins” (i.e., occupies the active site a greaterpercentage of the time)?arrow_forwardVmax for an enzyme-catalyzed reaction: A) generally increases when pH increases. B) is limited only by the amount of substrate supplied. C) is twice the rate observed when the concentration of substrate is equal to the Km. D) is unchanged in the presence of a uncompetitive inhibitor. E) increases in the presence of a competitive inhibitor.arrow_forward
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