Abstract
Two recent examples in X-ray structure analysis at opposite ends of the molecular weight range, in which very careful consideration of space group and diffraction symmetry was necessary to resolve all the associated problems, are described. Case 1 involves the structures of (1) transdiBromo (1,4,8,11-tetraazacyclotetradecane) chromium (III) bromide and (2) the corresponding trans-bromo-chloro compound. Both crystallise in space groupP42/m with unit cell dimensions sufficiently close to suggest that the structures are isomorphous. It is shown however that the structures are not superimposable or even related by simple rotation or inversion, but that it is necessary to apply a hypothetical glide operation in order to bring the structures into coincidence. The organic moieties are thus structural enantiomorphs in spite of existing in a centrosymmetric space group. Case 2 involves studies on a co-crystallised derivative of the enzyme RNase with deoxycytidylyl-3′–5′-deoxyguanosine (dCpdG). Preliminary X-ray precession photographs, from low quality crystals, indicated an orthogonal C-centred unit cell, but were unable to define the true diffraction symmetry, which wasnot orthorhombic. The true symmetry was discovered only after solving the structure in a second (erroneous) cell and careful inspection of the lattice and diffraction symmetry from the measured intensity values.
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Aguilar, C. F., Thomas, P. I., Moss, D. S., Mills, A., and Palmer, R. A. (1991)Biochim. Biophys. Acta 1118, 6–20.
Chattopadhyay, T. K., Palmer, R. A., Lisgarten, J. N., Wyns, L., and Gazi, D. M. (1992)Acta Crystallogr. C 48, 1756–1759.
Crowther, R. A. (1972) inThe Molecular Replacement Method (Rossman, M. G., ed.) (Gordon and Breach, NY), pp. 173–178.
Crowther, R. A., and Blow, D. M. (1967)Acta Crystallogr. A 23, 544–548.
Davies, E. K. (1986) CHEM-X, Chemical Design Ltd, Oxford.
Dodson, G. (1985) ALMN programme, CCP4 suite. Daresbury Laboratory, UK.
Dealwis, C. G., Janes, R. W., Palmer, R. A., Lisgarten, J. N., Wyns, L., and Gazi, D. M. (1992)Acta Crystallogr. C 48, 1754–1756.
Haneef, I., Moss, D. S., Stanford, M. J., and Borkakoti, N. (1985)Acta Crystallogr. A 41, 426–433.
Harris, G. W., Borkakori, N., Moss, D. S., Palmer, R. A., and Howlin, B. (1987)Biochimica Biophys. Acta 912, 348–356.
Hemmings, A. M., Lisgarten, J. N., Palmer, R. A., and Gazi, D. M. (1990)Acta Crystallogr. C 46, 205–207.
Hendrickson, W. A., and Fourmé, G. (1990) inSynchrotron Radiation Biophysics Hasnain E. (ed.), (Ellis Horwood, NY).
International Tables for X-Ray Crystallography, Volume I (1952) (Symmetry Groups) (Henry, N. F. M., and Lonsdale, K.), (Kynock Press, Birmingham, England).
Lisgarten, J. N., Palmer, R. A., Hemmings, A. M., and Gazi, D. M. (1990)Acta Crystallogr. C 46, 396–399.
Mills, A., Spink, N., Palmer, R. A., Wyns, L., Gupta, V., and Lisgarten, J. N. (1993)Acta Crystallogr., (In press).
Motherwell, W. D. S., and Clegg, W. (1978) PLUTO Programme for plotting molecular and crystal structures. Univ. of Cambridge, England.
Rossmann, M. G., and Blow, D. M. (1962)Acta Crystallogr. 15, 24–31.
Sheldrick, G. (1986) University of Gottingen.
Sheldrick, G. (1990) University of Gottingen.
Taylor, G., LATTICE Programme (Birkbeck College, Crystallography Department Programme Library, 1991).
Tickle, I. J., (Machin, P. ed.) (1985) Proceedings of Daresbury Laboratory.
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Palmer, R.A. Symmetry old and new: Some recent examples of the role of symmetry in X-ray analysis. J Chem Crystallogr 24, 51–60 (1994). https://doi.org/10.1007/BF01665345
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DOI: https://doi.org/10.1007/BF01665345