Isolation, crystallization in the macrogravitation field, preliminary X-ray investigation of uridine phosphorylase from Escherichia coli K-12. |
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| Authors: | A M Mikhailov E A Smirnova V L Tsuprun I V Tagunova B K Vainshtein E V Linkova A A Komissarov Z Z Siprashvili A S Mironov |
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| Affiliation: | Institute of Crystallography Academy of Sciences of the USSR, Moscow. |
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| Abstract: | Uridine phosphorylase (UPH) from Escherichia coli K-12 has been purified to near homogeneity from a strain harbouring the udp gene, encoding UPH, on a multicopy plasmid. UPH was purified to electrophoretic homogeneity with the specific activity 230 units/mg with a recovery of 80%, yielding 120 mg of enzyme from 3g cells. Crystals of enzyme suitable for X-ray diffraction analysis were obtained in a preparative ultracentrifuge. The packing of the molecules in the crystals may be described by the space group P2(1)2(1)2(1) with the unit cell constants a = 90.4; b = 128.8; c = 136.8 A. There is one molecule per asymmetric unit, Vm = 2.4. These crystals diffract to at least 2.5-2.7 A resolution. The hexameric structure of UPH was directly demonstrated by electron microscopy study and image processing. |
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