A preliminary time-of-flight neutron diffraction study on amicyanin from Paracoccus denitrificans

Crystals of the blue copper protein amicyanin suitable for neutron diffraction were grown by the sitting-drop method, followed by repeated macroseeding using solutions prepared with D2O. Although the crystal sizes were the same, crystals grown using solutions made up in H2O in the initial stages of macroseeding and solutions with D2O in later stages did not diffract neutrons well. However, when the protein was initially exchanged with buffered D2O and then crystallized and also macroseeded using solutions made up in D2O throughout, the crystals diffracted neutrons to high resolution. One of those crystals was used to collect a data set to a resolution of 1.9 angstrom.