Crystallization and preliminary X-ray diffraction analysis of the light-harvesting protein phycocyanin from the thermophilic cyanobacterium Synechococcus elongatus

Citation
Y. Toriumi et al., Crystallization and preliminary X-ray diffraction analysis of the light-harvesting protein phycocyanin from the thermophilic cyanobacterium Synechococcus elongatus, ACT CRYST D, 57, 2001, pp. 1326-1328
Citations number
19
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry & Analysis
Journal title
ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY
ISSN journal
0907-4449 → ACNP
Volume
57
Year of publication
2001
Part
9
Pages
1326 - 1328
Database
ISI
SICI code
0907-4449(200109)57:<1326:CAPXDA>2.0.ZU;2-U
Abstract
The crystallization and preliminary crystallographic study of phycocyanin f rom the thermophilic cyanobacterium Synechococcus elongatus is reported. Ph ycocyanin is composed of alpha- and beta -subunits consisting of 162 and 17 2 amino-acid residues, respectively. These associate to form an alpha beta heterodimer, which further associates to give a ring-shaped trimer (alpha b eta)(3). Two trimers bind head-to-head to form a hexamer (alpha beta)(6). P hycocyanin crystals have been obtained by the sitting-drop vapour-diffusion method with a precipitant solution containing 30%(w/v) PEG 4000 and 100 mM MES pH 7.5-8.0. Using synchrotron radiation, the crystals diffract to 2.0 Angstrom resolution. They belong to the trigonal space group R32, with unit -cell parameters a = b = 186.75 (3), c = 59.75 (4) Angstrom, alpha = beta = 90, gamma = 120 degrees. Assuming that the crystallographic triad is ident ical to the threefold axis of the hexamer and with three (alpha beta)(6) mo lecules in a unit cell, the calculated molar volume (V-M) is 2.64 Angstrom (3) Da(-1). This value corresponds to a solvent content of approximately 53 %, with one alpha beta heterodimer occupying the asymmetric unit.