"X-ray diffraction of protein crystals"

Date:
1954-1956
Reference:
PP/CRI/H/1/33
Catalogue details

Licence: In copyright

Credit: "X-ray diffraction of protein crystals". Source: Wellcome Collection.

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    3. case occurs, for example, amorío the myoglobins, in which it is found that crystals obtained from porpoise myoglobin snd from three dif erent species of whale give essentially the < D same i-ray diftpramffr Thus in special circumstances protein crystals can give limited information about identity of proteins. Crystallisation Nothing will be said about the search for the conditions under which crystals can be obtained from amorphous protein, as the protein chemist is in any ss. case familiar with this problem, and there appears to be no general rules to act as guides. It will be assumed that crystals of some sort have alrâedy been obtained. However protein crystals must be a certain size if they are to be studied conveniently b X-rays. The optimum is about 0. 3jnm in all directions, though preliminary ^o r k can sometimes be done on crystals as small as 0 .1 mm, or even smaller. The protein chemist is usually satisfied, if his crystals are lar^e enough to be seen in the microscope, so it will often ^jJ6utzÌÀj fir fleew&kc ÌUOIHJM ktoifM £Ut erb*»C!ht/b* 0*¡iklt ¿Li ¡fi.vfí Ä, ì h^ntCrc be necessary as a first step to grow big -er crystals^ There are man ways of doing this, but in essence they all consist in srrowinsr as few crystals as possible, and in growing these few rather slowly, so that fresh crystal nuclei cannot easily form. Proteins vary considerably: some may form quite large crystals without any special precautions, while others produce such small crystals fiat considerable effort must be expended to get the® larsre enough. An example of the first is chick