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A comparison between the crystal and solution structures of Escherichia coli asparaginase II

100%

Kozak M., Jurga S.

Acta Biochimica Polonica

2002

tom 49

nr 2

The small angle X-ray scattering (SAXS) pattern of the homotetrameric asparaginase II from Escherichia coli was measured in solution in conditions resembling those in which its crystal form was obtained and compared with that calculated from the crystallographic model. The radius of gyration measured by SAXS is about 5% larger and the maximum dimension in the distance distribution function about 12% larger than the corresponding value calculated from the crystal structure. A comparison of the experimental and calculated distance distribution functions suggests that the overall quaternary structure in the crystal and in solution are similar but that the homotetramer is less compact in solution than in the crystal.

Preliminary crystallographic studies of Y25F mutant of periplasmic Escherichia coli L-asparaginase

84%

Kozak M., Jaskolski M., Rohm K. H.

Acta Biochimica Polonica

2000

tom 47

nr 3

Periplasmic Escherichia coli L-asparaginase II with Y25F mutation in the active-site cavity has been obtained by recombinant techniques. The protein was crystallized in a new hexagonal form (P6522). Single crystals of this polymorph, suitable for X-ray diffraction, were obtained by vapor diffusion using 2-methyl-2,4-pentanediol as precipitant (pH 4.8). The crystals are characterized by a = 81.0, c = 341.1 A and diffract to 2.45 A resolution. The asymmetric unit contains two protein molecules arranged into an AB dimer. The physiologically relevant ABA'B' homotetramer is generated by the action of the crystallographic 2-fold axis along [1, -1, 0]. Kinetic studies show that the loss of the phenolic hydroxyl group at position 25 brought about by the replacement of Y with F strongly impairs kcat without significantly affecting Km.

Ograniczanie wyników

2 Acta Biochimica Polonica

2 Kozak M.

1 Jaskolski M.

1 Jurga S.

1 Rohm K. H.

1 2002

1 2000

Wyniki wyszukiwania

A comparison between the crystal and solution structures of Escherichia coli asparaginase II

Preliminary crystallographic studies of Y25F mutant of periplasmic Escherichia coli L-asparaginase