{'fraction_non_alphanumeric': 0.05492851768246802, 'fraction_numerical': 0.03686982693754703, 'mean_word_length': 5.073059360730594, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Crystallization and preliminary X-ray diffraction analysis of the light-harvesting protein phycocyanin from the thermophilic cyanobacterium Synechococcus elongatus.

The crystallization and preliminary crystallographic study of phycocyanin from the thermophilic cyanobacterium Synechococcus elongatus is reported. Phycocyanin is composed of alpha- and beta-subunits consisting of 162 and 172 amino-acid residues, respectively. These associate to form an alphabeta heterodimer, which further associates to give a ring-shaped trimer (alphabeta)(3). Two trimers bind head-to-head to form a hexamer (alphabeta)(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 A resolution. They belong to the trigonal space group R32, with unit-cell parameters a = b = 186.75 (3), c = 59.75 (4) A, alpha = beta = 90, gamma = 120 degrees. Assuming that the crystallographic triad is identical to the threefold axis of the hexamer and with three (alphabeta)(6) molecules in a unit cell, the calculated molar volume (V(M)) is 2.64 A(3) Da(-1). This value corresponds to a solvent content of approximately 53%, with one alphabeta heterodimer occupying the asymmetric unit.