ABSTRACT
We have already seen that much of the catalytic enhancement generated by enzymes derives simply from their binding substrates in close proximity, and having acidic and basic side chains placed at appropriate places. That is, enzymes do not in general need to do anything particularly ‘clever,’ and their remarkable rate enhancements are due not so much to subtle chemical reactivity or internal rearrangements as to rather straightforward physical principles, albeit arranged very precisely. This is an example of a major theme of this book, that most of what proteins do can be understood at a very simple ‘macroscopic’ level without needing to go into structural detail. This theme is pursued further in Chapter 8, where we will see that signaling depends mainly on an interplay of intramolecular and intermolecular protein interactions, and requires the same sort of physical principles. In other words, in these two aspects of protein function, the functionality derives mainly from the rates at which molecules bind and detach, and the rates at which they move randomly around the cell; the detailed inner workings of the proteins are interesting but do not need to be understood to get an idea of how the system works.
