The effect of ordering of internal water in thaumatin and lysozyme crystals as revealed by Raman method

The correlation between the relative intensity of water Raman band and crys tal quality was studied for thaumatin and tetragonal lysozyme crystals grow n under different conditions. The intensity variation of the band, revealed for the set of crystals was interpreted as being due to the different exte nts of ordering of internal water molecules. It was suggested that ordering is mainly relative to the alignment of the angle between the O-H bonds in water, since this angle serves as a normal coordinate for the symmetric ben ding vibration of H-O-H unit and the spectral width of the corresponding Ra man band (2v(2)) at 3212 cm(-1) appeared to be the main indicator of orderi ng. The assumption that the ordering of internal water molecules is relativ e to the overall protein crystal perfectness was verified by comparison of crystal scores obtained via the Raman and diffraction methods. The assessme nt of the crystal perfectness via these two methods seems to show some corr elation. If this correlation confirmed, the noninvasive Raman spectroscopy may be used to monitor crystal quality during its growth. (C) 2000 Elsevier Science B.V. All rights reserved.