The Crystal Structure of Rhombohedral 2 Zinc Insulin

In the latter half of 1969 the interpretation of an electron-density map at 2.8A ' resolution of rhombohedral 2 zinc insulin (porcine) was pre-sented (Adams et al., 1969). A more thorough analysis of this map has led to some small changes in the original structure though the overall organization remains unchanged. Coordinates for all the atoms in the two independent molecules have been derived (Blundell et al., 1971a). Initially atomic coordinates were obtained from a model built using the Richards ' optical super-position device and as such were only an approxi-mate set. These were subsequently modified with the help of computer programs written by R. Diamond (1966) and M. Levitt (unpublished), the