09 Regulation - B iochemis ry E duca ion Department of...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: B iochemis ry E duca ion Department of iochemistry & Molecular iology University of New Mexico BIOC 423 Int oducto y Biochemist y Regulation of Enzyme Activity OBJECTIVES • Understand the four major regulatory strategies that control enzyme activity. Know examples of each strategy and their molecular mechanisms. • Know the basic reactions catalyzed by protein kinases, phosphatases and serine proteases. • Be able to define the terms zymogen and proprotein, and know examples of each. • Understand the concept of a "cascade mechanism" and be able to give examples. • Be able to discuss the reaction kinetics of an allosteric enzyme and provide correct assignments of inhibitors and activators from kinetic data OUTLINE Genetic Control (Expression and Compartments) Example: Glucose Synthesis Covalent Modification Reversible Protein Kinase Protein Phosphatase Irreversible Zymogens (Digestion, Clotting, Complement) Allosteric Regulation Aspartate transcarbamoylase Generic regulatory schemes CTP: Negative allosteric effector ATP: Positive allosteric effector LECTURE As we begin our study of metabolism, there are three things that are absolutely essential to understanding a metabolic pathway. These three elements are: regulation, regulation, and regulation. It is absolutely critical to control the flow of carbon, reducing power and energy through any metabolic pathway. To understand the importance of regulation some instructors draw analogies between metabolic regulation and traffic flow patterns while other instructors point out the similarities between metabolism and a system of interconnected lakes and rivers. In either case, the point of these comparisons is to emphasize the importance of turning on and off enzymatic reactions, and remembering that in the body reactions do not happen in isolation. Consider, for example, the following two reactions that happen in your liver cell. The enzyme hexokinase converts glucose to glucose 6-phosphate. While in the same cell glucose 6-phosphatase converts glucose 6-phosphate back to glucose. If both of the above reactions were allowed to proceed uncontrolled this would set up a futile cycle that would serve only to deplete all cellular ATP. Because of the importance of regulation, not unexpectedly, there are several different regulatory patterns that we will encounter in our future study of metabolic pathways that prevent situations such as the futile cycle illustrated above. These regulatory patters differ in the speed at which control of a reaction can be implemented and in the nature of the regulatory mechanism itself. Gene Expression and Compartmentalizaton The most fundamental of the regulatory strategies is that of gene expression. By gene expression we mean the amount of a specific enzyme that is synthesized. For this regulatory mechanism when additional enzyme activity is needed, the gene is activated resulting in increased synthesis of the specific protein. Obviously the speed at which this type of regulation can be implemented is limited by the rate of gene...
View Full Document

This note was uploaded on 04/05/2008 for the course BIOCHEM 423 taught by Professor Osgood during the Spring '08 term at New Mexico.

Page1 / 9

09 Regulation - B iochemis ry E duca ion Department of...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online