Locations of Bromide Ions in Tetragonal Lysozyme Crystals

Lim, Kap; Nadarajah, Arunan; Forsythe, Elizabeth L.; Pusey, Marc L.

Anions have been shown to play a dominant role in the crystallization of chicken egg-white lysozyme from salt solutions. Previous studies employing X-ray crystallography have found one chloride ion binding site in the tetragonal crystal form of the protein and four nitrate ion binding sites in the monoclinic form. In this study the anion positions in the tetragonal form were determined from the difference Fourier map obtained from lysozyme crystals grown in bromide and chloride solutions. Five possible anion-binding sites were found in this manner. Some of these sites were in pockets containing basic residues while others were near neutral, but polar, residues. The sole chloride ion binding site found in previous studies was confirmed, while four further sites were found which corresponded to the four binding sites found for nitrate ions in monoclinic crystals. The study suggests that most of the anion-binding sites in lysozyme remain unchanged even when different anions and different crystal forms of lysozyme are employed.

Document ID

19990071232

Acquisition Source

Marshall Space Flight Center

Document Type

Reprint (Version printed in journal)

External Source(s)

doi:10.1107/S0907444998002844

Authors

Date Acquired

September 6, 2013

Publication Date

January 1, 1998

Publication Information

Publication: Acta. Crystallographica

Publisher: International Union of Crystallography

Issue: Section D

ISSN: 0907-4449

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Public

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