Structure and function of proteins.

Abstract

It is now many years since Linderstr6m-Lang suggested that the threedimensional conformation of a protein is the end result of its primary, secondary and tertiary structures. The protein's primary structure is represented by its amino acid sequence and the secondary structure by its tr-helices and E-sheets; its final three-dimensional conformation is its tertiary structure. Another fundamental insight came from Sanger, who showed--much to the surprise of many scientists at that time--that each protein possesses a well-defined amino acid sequence. He led the way by identifying the amino acid sequence of insulin, and as a result of his work and that of others there are now many proteins whose amino acid sequences are known. Linus Pauling deciphered the secondary structure of proteins by postulating the existence of helices and peptide sheets in fibriUar and globular proteins. Confirmation of this hypothesis came from X-ray analysis of different poly-oc-amino acids, the simple peptide polymers which were synthesized and studied in my laboratory in Rehovot. Perutz and Kendrew ,.successfully used X-ray techniques to elucidate the three-dimensional structure of two globular proteins, myobloglobin and haemoglobin. It was no easy task--Max Perutz devoted nearly 20 years of his life to it--but the effort proved to be worthwhile. The development of modern X-ray techniques represented a methodological breakthrough, which meant that it was not possible to determine the threedimensional structure of practically every protein or nucleic acid that could be oriented or crystallized. Newer techniques such as two-dimensional nuclear magnetic resonance (NMR) are gradually catching up, at least as far as low molecular weight proteins are concerned, and have already provided valuable information on the behaviour of biopolymers in solution.