X-Ray Analysis and Protein Structure

This appears to be a critical moment at which to try to write an account of the evidence from X-ray analysis on protein structure. Since the contribution that Fankuchen wrote for the Cold Spring Harbor Symposium in 1941, X-ray measurements have been extended to cover, not only more crystalline pro-teins of molecular weights varying from 10,000,000 to 12,000, but also certain groups of crystalline pep-tides and one or two more amino acids. We can now give a list of compounds examined by X-ray meth-ods, increasing in molecular weight by multiples of about 3 or 4, from amino acids such as glycine and alanine to the bushy stunt virus. At every molecular weight step it would be useful to observe an added variety of crystal structures, and survey work on