Kinetics Analyzer1

Fibril formation in 10 mM phosphate was followed by monitoring turbidity at 313 nm as a function of time. The amplitude of the plateau value is a function of both the amount of reconstituted fibrils and their final width. Fibrillogenesis kinetics under these conditions (10 °C, 10 mM phosphate, pH 7) were instantaneous whichever collagen was used. No significant difference was observed between the kinetics for Het I and rColl I (Fig. 7). The morphology of the fibrils obtained after completion of turbidity measurements was identical to that previously shown (Fig. 6). Thus, the formation of striated fibrils with unhydroxylated collagen, contrary to hydroxylated homotrimeric collagen I, is dependent on the low ionic strength of the buffer. As shown for native collagens, fibril formation increased substantially the melting temperature of the recombinant collagen which reached 36 °C instead of 30 °C for the isolated molecules (data not shown).