Biochemistry: The Molecular Basis of Life
6th Edition
ISBN: 9780190209896
Author: Trudy McKee, James R. McKee
Publisher: Oxford University Press
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Chapter 16, Problem 2Q
Summary Introduction
To review:
The concentration of cAMP(cyclic adenosine monophosphate) formed by five hormone-receptor binding events if a single hormone binding event lasts for 2.3 seconds and the turnover number is 350 cAMP molecules per second, and the amplification effect of this.
Introduction:
GTP (guanosine triphosphate)-αs/adenylate cyclase interacts for 2.3 seconds in a hypothetical cAMP-mediated signal transduction. Binding of the signal to G-protein-coupled receptors induces the binding of GTP-αs to adenylate cyclase. Adenylate cyclase is the enzyme, which converts AMP to cAMP.
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In studies trying to understand the regulation of hormone-sensitive adenylatecyclase, it was discovered that non-hydrolyzable GTP analogs and cholera toxin (that inhibits theGTPase activity of Gs ) were able to activate the enzyme in a sustained (irreversible) profile, thereforeindicating that GTP hydrolysis represents a deactivation (turn-off) regulatory step.a) Will these analogs or toxin have any effect on adenylate cyclase activity in the absenceof any added hormone?b) If you add an factor that increases the rate of GTPase hydrolysis of the Gs protein, willthis activate or inhibit the observed downstream effect upon addition of the hormone (this is in theabsence of GTP analogs or toxin). Explain your answer.
The physiological effects of epinephrine should in principle be mimicked by addition of cAMP to the target cells. In practice, addition of cAMP to intact target cells elicits only a minimal physiological response. Why? When the structurally related derivative dibutyryl cAMP (shown below) is added to intact cells, the expected physiological response is readily apparent. Explain the basis for the difference in cellular response to these two substances. Dibutyryl cAMP is widely used in studies of cAMP function.
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moles produced:
mol CAMP/s
Chapter 16 Solutions
Biochemistry: The Molecular Basis of Life
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Ch. 16 - Prob. 3RQCh. 16 - Prob. 4RQCh. 16 - Prob. 5RQCh. 16 - Prob. 6RQCh. 16 - Prob. 7RQCh. 16 - Prob. 8RQCh. 16 - Prob. 9RQCh. 16 - Prob. 10RQCh. 16 - Prob. 11RQCh. 16 - Prob. 12RQCh. 16 - Prob. 13RQCh. 16 - Prob. 14RQCh. 16 - Prob. 15RQCh. 16 - Prob. 16RQCh. 16 - Prob. 17RQCh. 16 - Prob. 18RQCh. 16 - Prob. 19RQCh. 16 - Prob. 20RQCh. 16 - Prob. 21RQCh. 16 - Prob. 22RQCh. 16 - Prob. 23RQCh. 16 - Prob. 24RQCh. 16 - Prob. 25RQCh. 16 - Prob. 26RQCh. 16 - Prob. 27RQCh. 16 - Prob. 28RQCh. 16 - Prob. 29RQCh. 16 - Prob. 30RQCh. 16 - Prob. 31RQCh. 16 - Prob. 32RQCh. 16 - Prob. 33RQCh. 16 - Prob. 34FBCh. 16 - Prob. 35FBCh. 16 - Prob. 36FBCh. 16 - Prob. 37FBCh. 16 - Prob. 38FBCh. 16 - Prob. 39FBCh. 16 - Prob. 40FBCh. 16 - Prob. 41FBCh. 16 - Prob. 42FBCh. 16 - Prob. 43FBCh. 16 - Prob. 44SACh. 16 - Prob. 45SACh. 16 - Prob. 46SACh. 16 - Prob. 47SACh. 16 - Prob. 48SACh. 16 - Prob. 49TQCh. 16 - Prob. 50TQCh. 16 - Prob. 51TQCh. 16 - Prob. 52TQCh. 16 - Prob. 53TQCh. 16 - Prob. 54TQCh. 16 - Prob. 55TQCh. 16 - Prob. 56TQCh. 16 - Prob. 57TQCh. 16 - Prob. 58TQCh. 16 - Prob. 59TQCh. 16 - Prob. 60TQCh. 16 - Prob. 61TQCh. 16 - Prob. 62TQCh. 16 - Prob. 63TQCh. 16 - Prob. 64TQCh. 16 - Prob. 65TQCh. 16 - Prob. 66TQCh. 16 - Prob. 67TQCh. 16 - Prob. 68TQCh. 16 - Prob. 69TQCh. 16 - Prob. 70TQCh. 16 - Prob. 71TQCh. 16 - Prob. 72TQCh. 16 - Prob. 73TQCh. 16 - Prob. 74TQCh. 16 - Prob. 75TQ
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