 | Acta Crystallographica Section D Acta Crystallographica Section D BIOLOGICAL CRYSTALLOGRAPHY |
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![[Figure 1]](wd5046fig1mag.jpg)
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Figure 1
A schematic drawing of VIL (vaporizing iodine labelling) and HYPER-VIL (hydrogen peroxide VIL) procedures applied to representative thaumatin crystals. (a) The target native crystals are prepared by the hanging-drop vapour-diffusion method. (b) A small droplet of iodine stock solution is placed next to the crystallization droplet on the cover glass. (c) Vaporized I2 molecules soon spread throughout the crystallization well and diffuse into the crystallization droplet. (d) After incubation, the crystals are coloured dark brown. (e) The HYPER-VIL technique employs an additional small droplet (∼1.0 µl) of 30% H2O2 hydrogen peroxide placed onto a crystallization bridge enclosed in the crystallization well. The droplet of hydrogen peroxide should be introduced into the crystallization well after the colouration of the target crystals by the application of VIL, or the hydrogen peroxide will redissolve I2 molecules in the iodine droplet, which would decrease the amount of I2 vapour diffusion. (f) As a result of the HYPER-VIL reaction, generation of oxygen bubbles and bleaching of the brown colour are observed in the crystallization droplet, which are good indicators of iodination. |
![[Figure 1]](wd5046fig1.jpg)
| BIOLOGICAL CRYSTALLOGRAPHY |
ISSN: 1399-0047
