ISSN:
1399-0047
Quelle:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Thema:
Chemie und Pharmazie
,
Geologie und Paläontologie
,
Physik
Notizen:
The crystallization and preliminary crystallographic study of phycocyanin from the thermophilic cyanobacterium Synechococcus elongatus is reported. Phycocyanin is composed of α- and β-subunits consisting of 162 and 172 amino-acid residues, respectively. These associate to form an αβ heterodimer, which further associates to give a ring-shaped trimer (αβ)3. Two trimers bind head-to-head to form a hexamer (αβ)6. Phycocyanin 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 Å resolution. They belong to the trigonal space group R32, with unit-cell parameters a = b = 186.75 (3), c = 59.75 (4) Å, α = β = 90, γ = 120°. Assuming that the crystallographic triad is identical to the threefold axis of the hexamer and with three (αβ)6 molecules in a unit cell, the calculated molar volume (VM) is 2.64 Å3 Da−1. This value corresponds to a solvent content of approximately 53%, with one αβ heterodimer occupying the asymmetric unit.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1107/S0907444901011969
Permalink
