THE BIOLOGICAL ACTIVITY OF PROTEINS IN RELATION TO STRUCTURE
We may almost define the life sciences as those concerned with the elucidation of the mechanisms by which molecules exert their specific actions on living cells. In the case of many simple inorganic ions and organic molecules it has been possible to arrive at an approximate understanding of their mechanism of action. We have some understanding, for example, of the physiological sequelae of raising or lowering the tonicity of body fluids by the administration or withdrawal of sodium chloride. Similarly, the aberrations in the synaptic transmission of nerve impulses following the administration of physostigmine may be partially explained by the action of this drug on the enzyme acetylcholinesterase. It is a tribute to cellular complexity that even such well-studied systems as these continue to be frontiers of research and speculation among those individuals who are fully conversant with them.
Protein chemists naturally feel that the most likely approach to the