The subject of this study was the analysis of solubility, particle interactions and aggregation behavior of lumazine synthase from Bacillus subtilis. Lumazine synthase crystallizes in sodium/potassium phosphate buffer, pH 8.7. Contrary to the decrease in solubility with increasing salt concentration, the osmotic second virial coefficient remains almost constant and reveals the same slight attractive interactions under storage and crystallization conditions. In search of protein clusters that are involved in and accompany crystal nucleation, supersatured solutions of lumazine synthase were studied by dynamic light scattering and cryo transmission electron microscopy. As predicted by the classical nucleation theory, increased supersaturation facilitated the nucleation of crystals. This was accompanied by an increased detection of aggregates until the light scattering spectra were dominated by uncorrelated intensity fluctuations caused by a few but large aggregates, presumably microcrystals. Electron micrographs of supersaturated solutions showed network-like assemblies of lumazine synthase molecules and in addition lumazine synthase clusters with a linear arrangement. Even in supersaturated solutions of lumazine synthase where no nucleation took place, aggregates were detected by dynamic light scattering. In connection with atomic force microscopy studies carried out in the laboratory of Prof. Peter Vekilov at the University of Houston, Department of Chemical Engineering, Texas, USA, these aggregates were identified as dense liquid droplets of lumazine synthase that are metastable in respect to the original and the crystal phase. At low supersaturations these liquid droplets are the only source of new crystal growth layers.     «

The subject of this study was the analysis of solubility, particle interactions and aggregation behavior of lumazine synthase from Bacillus subtilis. Lumazine synthase crystallizes in sodium/potassium phosphate buffer, pH 8.7. Contrary to the decrease in solubility with increasing salt concentration, the osmotic second virial coefficient remains almost constant and reveals the same slight attractive interactions under storage and crystallization conditions. In search of protein clusters that are...     »

Gegenstand dieser Arbeit war die Bestimmung der Löslichkeit, der Molekülwechselwirkungen und des Aggregationsverhaltens von Lumazinsynthase unter Kristallisationsbedingungen in Na/K-Phosphat-Puffer. Lumazinsynthase zeigte die gleichen, geringfügig attraktiven Wechselwirkungen unter Kristallisations- wie auch unter nicht-Kristallisationsbedingungen. In Übereinstimmung mit der klassischen Keimbildungstheorie führt eine Steigerung der Übersättigung zu vermehrter Keimbildung von Kristallen. Damit einhergehend wurden mittels dynamischer Lichtstreuung vermehrt Aggregate detektiert, bis die Spektren von unkorrelierten Intensitätsschwankungen weniger, aber großer Teilchen, wahrscheinlich Mikrokristalle, überlagert wurden.     «

Gegenstand dieser Arbeit war die Bestimmung der Löslichkeit, der Molekülwechselwirkungen und des Aggregationsverhaltens von Lumazinsynthase unter Kristallisationsbedingungen in Na/K-Phosphat-Puffer. Lumazinsynthase zeigte die gleichen, geringfügig attraktiven Wechselwirkungen unter Kristallisations- wie auch unter nicht-Kristallisationsbedingungen. In Übereinstimmung mit der klassischen Keimbildungstheorie führt eine Steigerung der Übersättigung zu vermehrter Keimbildung von Kristallen. Damit ei...     »