BIOCHEMISTRY - L. Stryer - 1984

VOLUME 2

PART II GENERATION AND STORAGE OF METABOLIC ENERGY

Class="center">Model of acetyl coenzyme A, a key intermediate in the generation of metabolic energy

CHAPTER 11 METABOLISM: BASIC CONCEPTS AND DESIGNATIONS

The concepts of conformation and dynamics developed in Part I, especially aspects concerning the Specificity and catalytic power of Enzymes, The regulation of their catalytic activity, and compartmentalization by membranes, now allow us to address two major questions in biochemistry:

1. How do Cells extract energy and reducing power from their environment?

2. How do cells synthesize the Building Blocks of their macromolecules?

These processes are carried out by a highly integrated system of Chemical Reactions that collectively constitute metabolism.

Even in a simple Organism like E. coli, there are at least a thousand different chemical reactions. At first glance, organizing these reactions might seem daunting. However, a deeper analysis reveals that metabolism is a highly coordinated system with many common motifs. Although the number of metabolic reactions is large, the number of reaction types is relatively small. Their mechanisms are usually quite simple. For example, a double bond is often formed by a dehydration reaction. Furthermore, a group of about one hundred molecules plays a central role in all forms of life. Moreover, there are common regulatory mechanisms for metabolic pathways. The purpose of this chapter is to describe some of the General Principles and motifs of metabolism.