Structure X-ray diffraction studies

However, a structural (X-ray diffraction) study of the interaction of Et3PAuCl with the enzyme cyclophUin reveals that a histidine residue (see Table 29.2) displaces Cl . Unexpectedly, the gold(I) unit is bound by a histidine iV-donor in preference to the available cysteine 5-donors. 

Metals atoms (cations) pack closely together in a regular structure to form crystals. Arrangements in which the gaps are kept to a minimum are known as close-packed structures. X-ray diffraction studies have revealed that there are three main types of metallic structure hexagonal close packed, face-centred cubic close packed and body-centred cubic. 

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