The endoproteinase furin contains two essential Ca2+ ions stabilizing its N-terminus and the unique S1-specificity pocket
Acta Cryst. (2005). D61, 505–512
We have unequivocally determined the exact number and the three-dimensional localization of essential calcium sites within furin, a calcium-dependent endoproteinase of the prohormone/proprotein convertase (PC) family, employing a novel type of double difference Fourier map. This ‘difference DANO map’ was calculated from complete anomalous diffraction data collected on either side of the calcium K absorption edge in the softer X-ray regime and can also be applied to the unambiguous determination of all elements, for which an absorption edge can be accessed for diffraction experiments.
Manuel E. Than, Stefan Henrich, Gleb P. Bourenkov, Hans D. Bartunik, Robert Huber and Wolfram Bode
![[Furin]](https://www.iucr.org/__data/assets/image/0011/8975/actad.gif)
Ribbon plot of furin (yellow helices and red β-strands for the catalytic domain, P-domain entirely in cyan) together with the calcium-specific double difference Fourier map (‘difference DANO map’ in purple).
