1 / 13

Lecture 13

Lecture 13. Regulatory Strategies for Enzymes. Feedback Inhibition. Product acts as an inhibitor of initial enzymatic reaction. Ile inhibits threonine dehydratase. “Sigmoidal” Kinetics. Often regulated enzymes with multiple subunits. Allosteric enzymes. Phosphofructokinase.

makoto
Download Presentation

Lecture 13

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lecture 13 Regulatory Strategies for Enzymes

  2. Feedback Inhibition Product acts as an inhibitor of initial enzymatic reaction. Ile inhibits threonine dehydratase.

  3. “Sigmoidal” Kinetics • Often regulated enzymes with multiple subunits

  4. Allosteric enzymes

  5. Phosphofructokinase • Allosterically inhibited by: • ATP • Citrate • PEP • Allosterically stimulated by: • Fructose 2,6 bisphosphate • AMP, ADP

  6. Regulation by Covalent Modification • Phosphorylation • Tyr, Ser, Thr, His

  7. CH 2 PP i Regulation by Reversible Covalent Modification • Adenylylation • Tyr O Adenine O Enz P ATP O O Enz OH OH

  8. Glycogen Phosphorylase

  9. Glycogen Phosphorylase • Regulatory cascade • Hormonal signal • Allosteric regulation • Glucose and ATP are inhibitors • AMP is activator

  10. Zymogens:Regulation by Proteolytic Cleavage • Trypsinogen, chymotrypsinogen, and procarboxypeptidase are synthesized in pancreas • Activated in intestine by trypsin • Trypsin inhibited by pancreatic trypsin inhibitor

  11. Activation of Chymotrypsin In the intestine:

  12. Activation of Chymotrypsin

  13. Another way to regulate enzymatic reactions Regulate the production of the enzyme. Controlled at thelevel of transcription or translation Modification of mRNA Protein DNA RNA (positive or negative regulation) Controlled by transcription factors.

More Related