2D and 3D Location Paper First Draft

Date:
[1956]
Reference:
PP/CRI/H/2/11/1
Catalogue details

Licence: In copyright

Credit: 2D and 3D Location Paper First Draft. Source: Wellcome Collection.

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    f THE THEORY OP THE IS0M0KPH0U3 REPLACEMENT METIiOD FOR PROTEIN CRYSTALS - PART I By P. H, C, Orioli and Beatrice S. Magdoff latroauction ■ The work of Perutz and his colleagues (Green, Ingram and Perutz, 195b; Bragg and Perutz, 1954) has shown that the isomorphous replacement method can he applied to protein crystals provided a sufficiently heavy atom is used. Since other methods of attack on protein crystals have so far either failed or been inconclusive, it seems probable that no serious progresa can be made uniese this method is,applied, This aeries of papers deal.with some of the theoretical problems which have arisen in connection with the method. Two problems are considered in this paper. The first concerns the average change in intensity produced by adding extra atoms to the crystal, the rest of the unit cell remaining the same. The second deals with the average change of intensity produced by small shifts of the protein molecules, or by slight changes in the unit cell dimensions, #»@ have considered the second problem because it has been shown for ribonuclease that such changes occur ( Magdoff and Crick, ) and may make It difficult to apply the isomorphous replacement method very far out in reciprocal space, A further paper considers the problem of locating the