Letter | Published:

The Two Crystalline Modifications of Insulin

Naturevolume 140pages149150 (1937) | Download Citation



PROF. E. B. MATHEWS' first examination of Abel's crystalline insulin showed the presence of two types of insulin crystals1. One of these, the so-called prismatic or needle variety, had marked birefringence and a development of faces strongly suggestive of rhombohedral symmetry, the crystals being elongated along the trigonal axis. Crystals of this type are commonly wedge-shaped, and very small wedge-shaped crystals have also been obtained by Scott2 by crystallization of insulin from acetate buffers at pH. 5·2. The more common variety of insulin crystals are those obtained first by Abel3 from phosphate buffers at pH 6·2. These are very small flat rhombohedra appearing isotropic as usually viewed along the trigonal axis, but having actually positive birefringence. X-ray examination has here shown the presence of a simple rhombohedral unit cell4. It has been usual in the literature to describe these two forms—prismatic and rhombohedral—as polymorphic modifications5.

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  1. 1

    Abel, J. J., Geiling, E. M. K., Rouiller, C. A., Bell, F. K., and Wintersteiner, O., J. Pharm. Exp. Ther., 31, 84 (1927).

  2. 2

    Scott, D. A., Trans. Roy. Soc. Canada, (iii), 26, 275 (1932).

  3. 3

    Abel, J. J., Proc. Nat. Acad. Sci., 12, 132 (1926).

  4. 4

    Crowfoot, D., NATURE, 135, 591 (1935).

  5. 5

    cf. “Insulin” by D. W. Hill and F. O. Howitt (p. 51).

  6. 6

    cf. Astbury, W. T., Dickinson, S., and Bailey, K., Biochem. J., 29, 235 (1935).

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  1. Dept. of Mineralogy, Oxford



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