Preliminary study of a phase transformation in insulin crystals using synchrotron-radiation Laue diffraction

Synchrotron-radiation Laue diffraction photographs have been recorded showing the transformation of single 4Zn insulin crystals [a=80.7 (1), c=37.6 (1) A, space group R3] to 2Zn insulin [a=82.5 (1), c=34.0 (1) A, space group R3]. The transformation was brought about by changing the mother liquor in the capillary in which the crystal was mounted. Photographs were taken at 10 min intervals (exposure time 3 s) from 0.5 h after mounting. They showed initially a well ordered 4Zn insulin crystal (dmin ca 2.3 A), then a poorly ordered, sometimes multiple, crystal, and finally a 2Zn insulin crystal, about as well ordered as the initial crystal. (orig.)