The Genetic Control of Tertiary Protein Structure: Studies With Model Systems

At the present time it is generally assumed that most, if not all, proteins possess well-defined structures. This assumption is based on several kinds of evidence: (1) the finding that many proteins have unique amino acid sequences, with specific intrachain disulfide bonds; (2) the ability to determine the three-dimensional configuration (tertiary structure) and, in some instances, even portions of the amino acid sequence of proteins such as myoglobin and hemoglobin by X-ray crystallographic methods; (3) the highly reproducible physical-chemical properties of a large number of proteins; and (4) the great degree of configurational specificity which appears necessary for enzymic activity. When one considers the complexity of the tertiary structure of a “native” protein, it seems reasonable to inquire into how a newly-made protein arrives at its three-dimensional configuration.