CHAPTER 19 - Enzymes as Biological Catalysts (MOL S11)

CHAPTER 19 - Enzymes as Biological Catalysts (MOL S11) -...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 19: Enzymes as Biological Catalysts 1 CHAPTER 19: ENZYMES AS BIOLOGICAL CATALYSTS 19.1 INTRODUCTION: How Does HIV Reproduce Itself in Human Cells? 19.1.1 HIV Targets the Cells of the Immune System HIV infects the cells of the immune system and utilizes the cellular machinery to make copies of itself. 19.1.2 The Importance of Enzymes in HIV Replication HIV relies on three key enzymes are different stages of its life cycle. 19.2 HIV PROTEASE 19.2.1 HIV Protease Belongs to a General Class of Enzymes HIV protease belongs to a class of enzymes called aspartic acid proteases that cut peptide bonds. 19.2.2 Structure of HIV Protease The enzyme has a two-fold symmetry with a large binding pocket for the polypeptide substrate. 19.2.3 The Catalytic Mechanism of HIV Protease The enzyme achieves its catalytic reaction using two aspartic acid sidechains in the active site. 19.3 GENERAL THEMES IN ENZYME CATALYSIS 19.3.1 The Stages of Enzyme Reactions The enzyme-substrate complex leads to stabilization of the transition state and release of products. 19.3.2 How Does An Enzyme Recognize Its Substrate? An enzyme binds to a specific substrate by using complementary structural and chemical interactions. 19.4 CHAPTER SUMMARY
Background image of page 1

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

View Full DocumentRight Arrow Icon
Chapter 19: Enzymes as Biological Catalysts 2 19.1 INTRODUCTION: How Does HIV Reproduce Itself in Human Cells? We are all painfully aware that AIDS (A cquired I mmune D eficiency S yndrome) is among the most severe disease outbreaks in human history. Since the 1980’s, when researchers first recognized the appearance of a new and frequently fatal infection, we have known that the cause of AIDS is a virus called HIV (Human Immunodeficiency Virus). Still, at the time of this writing, no general vaccine is available for combating HIV. Instead, a series of anti-viral drugs has been developed that allows patients to survive for many years. These drugs function as inhibitors of particular steps in the HIV life cycle , the pathway by which the virus infects human immune cells and multiplies. In order to replicate itself, HIV requires several enzymes to infect its target cells and produce new virus particles. Enzymes function as biological catalysts that speed up biochemical reactions ; the vast majority of enzymes are protein molecules, although a few enzymes are made from strands of RNA. Enzymes obey the same principles of catalysis that we have studied in the previous chapter, but they also differ from metal catalysts in several significant ways (see Box 19.1). This chapter begins with an overview of the HIV life cycle and the important roles that enzymes play in HIV replication. We then look in more detail at the HIV protease enzyme , which is involved in one of the later stages of producing new HIV particles. In the next chapter we will see how certain drugs have been designed to block the HIV protease and provide a therapy for AIDS patients 19.1.1 HIV Targets the Cells of the Immune System Viruses exist at the fuzzy boundary between “living” and “non-living.” In general,
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 24

CHAPTER 19 - Enzymes as Biological Catalysts (MOL S11) -...

This preview shows document pages 1 - 3. Sign up to view the full document.

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