The Nature of Some Ion-Protein Complexes

In many of its aspects, the problem of ion-protein interactions is one to which biologists have devoted their attention for almost a century. Physiologists, in particular, have long been interested in the excitatory or inhibitory effects of specific anions and cations on nerve activity, or on other biological responses. Similarly, in enzymatic reactions, the biochemist has found the concept of enzyme-substrate combinations a very fruitful model for the interpretation of metabolic reactions. A priori, there is no reason to expect, of course, that all of these interactions embody a common mechanism or similar types of forces. Nevertheless, many of these phenomena can be described in terms of a picture involving actual binding of the small ion by the macromolecular protein. There has been a great deal of interest, therefore, particularly in recent years, in investigations which might give some insight into the nature of these ion-protein complexes.