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Overcoming a hemihedral twinning problem in tetrahydrofolate‐dependent O ‐demethylase crystals by the microseeding method
Author(s) -
Harada Ayaka,
Sato Yukari,
Kamimura Naofumi,
Venugopalan Nagarajan,
Masai Eiji,
Senda Toshiya
Publication year - 2016
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 37
ISSN - 2053-230X
DOI - 10.1107/s2053230x16018665
Subject(s) - crystal twinning , crystallography , resolution (logic) , diffraction , crystal (programming language) , demethylase , materials science , chemistry , physics , optics , biochemistry , computer science , gene , programming language , microstructure , artificial intelligence , epigenetics
A tetrahydrofolate‐dependent O ‐demethylase, LigM, from Sphingobium sp. SYK‐6 was crystallized by the hanging‐drop vapour‐diffusion method. However, the obtained P 3 1 21 or P 3 2 21 crystals, which diffracted to 2.5–3.3 Å resolution, were hemihedrally twinned. To overcome the twinning problem, microseeding using P 3 1 21/ P 3 2 21 crystals as microseeds was performed with optimization of the reservoir conditions. As a result, another crystal form was obtained. The newly obtained crystal diffracted to 2.5–3.0 Å resolution and belonged to space group P 2 1 2 1 2, with unit‐cell parameters a = 102.0, b = 117.3, c = 128.1 Å. The P 2 1 2 1 2 crystals diffracted to better than 2.0 Å resolution after optimizing the cryoconditions. Phasing using the single anomalous diffraction method was successful at 3.0 Å resolution with a Pt‐derivative crystal. This experience suggested that microseeding is an effective method to overcome the twinning problem, even when twinned crystals are utilized as microseeds.