The Molecular Structure of Amino Acids

The last decade has seen great progress in the studyof the structure and functions of living organisms at the molecular level; molecular biology has become a new branch of science [1-16]. One of the major problems of molecular biology concerns the structure of proteins. Some information about protein structure is provided by the electron microscope by the ultracentrifuge and by small-angle x-ray scattering; the last gives the fullest information about the atomic structure of protein molecules but x-ray study of biological objects represents a difficult and laborious task. In this way the struc- tures of three proteins have been established: hemoglobin myoglobin [2 8J and lysozyme [10]; work has begun on ribonuclease insulin chymo- trypSin carboxypeptidase and so on [14-16]. A knowledge of the structures of amino acids and peptides is of con- siderable value in elucidating the structure and functions of proteins. Near- ly all proteins consist largely of 22 principal amino acids which are linked together in polypeptide chains. The peptide link always arises between an a-amino group and the carboxyl group in the next amino acid residue so all polypeptide chains have the same backbone to which are attached dif- ferent radicals R (Fig. 1).