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od 2020-09-20

Title: Preliminary crystallographic studies of Y25F mutant of periplasmic Escherichia Coli L-asparaginase

Source: Acta Biochimica Polonica

Year : 2000

Abstract:

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 (P6(5)22). 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 Angstrom and diffract to 2.45 Angstrom 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 a-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 k(cat) without significantly affecting K-m.

DOI: 10.18388/abp.2000_3998   (Pobrane:  2021-01-10)