Lecture 7 8. 1 Major Modes of Regulation 8.2 Inhibiting Enzyme Activity 8.3 Modification of Enzymes 8.4 dNA Binding Proteins 8.5 Negative Control of Transcription Repression and Induction 8.6 Positive Control of transcription
Lecture 7 • 8.1 Major Modes of Regulation • 8.2 Inhibiting Enzyme Activity • 8.3 Modification of Enzymes • 8.4 DNA Binding Proteins • 8.5 Negative Control of Transcription: Repression and Induction • 8.6 Positive Control of Transcription
Regulation different conditions require different strategies changes in nutrients available sporulation impractical to make every protein excess proteins may be detrimental allows specific response activities can be regulated at multiple levels
Regulation • different conditions require different strategies – changes in nutrients available – sporulation • impractical to make every protein • excess proteins may be detrimental • allows specific response • activities can be regulated at multiple levels
Different Regulatory Mechanisms Regulate Regulate enzyme synthesis enzyme activity At translation At transcription Substrate Product No product Enzyme a En zyme No enzyme Translation No mRNA Transcription 米 》 Gene A Gene B Gene C Gene D Figure 8.1
Figure 8.1 Different Regulatory Mechanisms
Feedback Inhibition Starting material Enzyme A First intermediate Enzyme B Second intermediate Enzyme C Third intermediate Enzyme D End product Figure 8.2
Figure 8.2 Feedback Inhibition
Allosteric Effector Substrate Allosteric site binding site Allosteric flector Substrate Conformational change in substrate binding site: enzyme reaction inhibited Substrate cannot bind No enzyme Figure 8.3
Figure 8.3 Allosteric Effector