"The three-dimensional Patterson function of ribonuclease"

Date:
[1956]
Reference:
PP/CRI/H/2/9
Catalogue details

Licence: In copyright

Credit: "The three-dimensional Patterson function of ribonuclease". Source: Wellcome Collection.

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    form 2f 2 eap(-.A/d a ) to figure 1, especially as the number of ordered atoms in the crystal is not known. Preliminary measurement^ to put the data on an absolute scale have been made by Dr. Thomas Furnas, Jr. and his provisional value has been used throughout this paper. The dotted line ofj^Figure 1 shows the curve-- fj* (s)exp (-4.56/d 2 ), and these values were used to remove the origin peak. (b) The_Patterson The Patterson was plotted by a novel method. The actual OM sheets contained the figures set out in a rectangular array. Contour# were first drawn on these sheets. They were naturally distorted from the correct shape because the basic array did not correspond to the monoclinic cell. Correct contours were then drawn onto the final sheets, having an underlying grid of the correct size and shape, by comparing the points where the contours intercepted their grids in the two cases. This method proved to be quicker than first copying all the computed figures onto the scaled sheets and then drawing the contours. Each contour represents a level of about 100 electrons*/^, ^ Vv o-t-r-s copy of each of the 21 sections of the three-dimensional Patterson, from y-0 to y-ZCP/éO^ t.h ffte IBM sheets showing the—f i gu-pes from which they were plotted, helfe.been deposited at ^ and copies can be obtained f***- ^ Aw-we^. I> e e—Ywe<-J^y • As might be expected from Figure 1 the Patterson has a very marked o 5A shell. This shell Is not completely isotropic, more vectors falling in one general direction (about 30® from ^ in the direction of c) than in the plane perpendicular to this direction. This can be seen from Figure Z which shows a^stereogram of the peak height of the^SA shell in all directions. The basal section of the Patterson^(Figure S) also shows this. ISi-üirr2E-£ié2S-HC®£i The other striking feature of the Patterson is the markedly greater variations in height of the contours in the basal and Harker sections (y»0 and y-b/2) than in the general sections, as can be seen from studying Figure» ^,4,5, and 6. This was at first sight very puzzling, as the effect onl^ extends a smell distance (^IA) on either side of these sections in the y direction. This is shown in Table 1, which lists the number of peaks with heights greater than the third and fourth £ ft . «M ^<_e$ (*V\fW> Ö iaJç -H, LCOv-c*»^ ty Cv^-i| r ^ il j Lt