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Expression of a selenomethionyl derivative and preliminary crystallographic studies of human cystatin C

1999; Wiley; Volume: 55; Issue: 11 Linguagem: Inglês

10.1107/s090744499901121x

1399-0047

Maciej Kozak, Elżbieta Jankowska, Robert Janowski, Zbigniew Grzonka, Anders Grubb, Marcia Alvarez Fernandez, Magnus Abrahamson, Mariusz Jaskólski,

Porphyrin Metabolism and Disorders

Human cystatin C, a protein with amyloidogenic properties and a potent inhibitor of papain-like mammalian proteases, has been produced in its full-length form by recombinant techniques and crystallized in two polymorphic forms: cubic and tetragonal. A selenomethionyl derivative of the protein, obtained by Escherichia coli expression and with complete Met→Se-Met substitution confirmed by mass spectrometry, amino-acid analysis and X-ray absorption spectra, was crystallized in the cubic form. A truncated variant of the protein, lacking ten N-terminal residues, has also been crystallized. The crystals of this variant are tetragonal and, like the two polymorphs of the full-length protein, contain multiple copies of the molecule in the asymmetric unit, suggesting oligomerization of the protein.