Enzyme Acatalyzes the reactions S to P and has a KM of 50μMand a Vmaxof 100nMs1. Enzyme Bcatalyzes the reaction SQ and has a KM of 5mMand a Vmax of 120nMs1. When 100μM of S is added to a mixture containing equivalent amounts of enzymes A andB , after 1minute which reaction product will be more abundant: P or Q?

Short Answer

Expert verified

The product P would be more abundant because the enzyme A has a lower KM.

Step by step solution

01

Introduction

The substrate concentration at which the reaction rate is 50% of Vmax is known as Km (also known as the Michaelis constant). Vmax shows the reaction of maximum velocity at which all enzymes are saturated with the substrate.

02

Product P will be abundantly produced

The enzyme A catalyzes the reactionSP,

KM=0.05mMVmax=100nMs1

The enzyme B catalyzes the reaction SQ,

KM=5mMVmax=120nMs1

It can be inferred from the data that Vmaxis almost the same for both enzymes A and B. This depicts that the relative efficiency of the enzymes depends on their KM values. Therefore, product P will be abundantly produced because enzyme A has a lower KM value.

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Most popular questions from this chapter

Enzyme X and enzyme Y catalyze the same reaction and exhibit the v0 versus [S] curves shown below. Which enzyme is more efficient at low [S]? Which is more efficient at high [S]?

At what concentration of S (expressed as a multiple of KM ) will v0=0.95Vmax?

Ethanol in the body is oxidized to acetaldehyde (CH₃CHO) by liveralcohol dehydrogenase (LADH). Other alcohols are also oxidized byLADH. For example, methanol CH₃OH), which is mildly intoxicating, isoxidized by LADH to the quite toxic product formaldehyde (CH₂O). Thetoxic effects of ingesting methanol (a component of many commercialsolvents) can be reduced by administering ethanol. The ethanol acts as acompetitive inhibitor of the methanol by displacing it from LADH. Thisprovides sufficient time for the methanol to be harmlessly excreted bythe kidneys. If an individual has ingested 100 mL of methanol (a lethaldose), how much 100 proof whiskey (50% ethanol by volume) must beimbibe to reduce the activity of his LADH toward methanol to 5% of itsoriginal value? The adult human body contains -40 L of aqueous fluidsthroughout which ingested alcohols are rapidly and uniformly mixed.The densities of ethanol and methanol are both 0.79 g .cm-3. Assumethe KM values of LADH for ethanol and methanol to be 1.0 X 10⁻³Mand 1.0 X 10⁻²M, respectively, and that KI = KM for ethanol.

You are trying to determine the KM for an enzyme. Due to a labmishap, you have only two usable data points:

Substrate concentration (μM)

Reaction velocity (μM s⁻¹)

1

5

100

50

Use these data to calculate an approximate value for KM. Is this valuelikely to be an overestimate or an underestimate of the true value? Explain.

Write the Lineweaver–Burk (double reciprocal) equation and describe the features of a Lineweaver–Burk plot.

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