CHAPTER 1
 BACKGROUND AND SIGNIFICANCE

 Introduction

 The premiere of Peter Mitchell's chemiosmotic theory in 1961 eventually resulted

in the major breakthrough of the characterization of F1Fo ATP synthases. Basically, his

theory stated that protons are pumped across energy transducing membranes, thereby

creating an electrochemical gradient of protons (1). This proton gradient, also known as

the proton-motive force, consists of two components: i) a chemical component due to the

concentration gradient of protons and ii) an electrical component, or membrane potential,

due to the positive charge of the protons (H ). As a result, one side of the membrane is

more positive than the other. The potential energy of this gradient can then be transduced

to chemical energy or utilized to perform work when the protons diffuse back across the

membrane from the higher to the lower potential (2). The protons can diffuse across the

membrane through specific transmembrane proton conductors, which can synthesize

adenosine 5'-triphosphate (ATP) or co-transport solutes, and in the case of bacteria drive

flagellar rotation.

 The ability to consume nutrients and convert them to energy is required of all living

organisms, from microscopic bacteria to plants to humans. The universal molecule of

biological energetic is ATP, and in almost all organisms, the central enzyme involved in

providing the maj ority of cellular ATP is F1Fo ATP synthase (3-6). F1Fo ATP synthases

are responsible for the production of ATP in the final step of processes called oxidative

phosphorylation and photophosphorylation. They provide the bulk of cellular energy in