Kinetics Analyzer1

Critical conditions allowing formation of striated fibrils from unhydroxylated recombinant collagen were identified by varying the ionic strength of the fibrillogenesis buffer. Under all other conditions (variations of pH and temperature), no striated fibrils were formed. Only when recombinant collagen was incubated in low ionic strength buffer (10 mM phosphate, pH 7) was striated fibril assembly observed. Under these conditions, cross-banded fibrils were predominant, and the measured periodicity was 65.9 ± 0.8 nm which is close to the 67 nm expected value (Fig. 6, A-C). Under the same conditions, Het I formed a meshwork of long and thin striated fibrils (Fig. 6, D and E), whereas Hom I only aggregated into non-banded fibrils (Fig. 6F). The rColl I fibrils were particularly heterogenous in size and morphology (Fig. 6, A-C). Fibril diameter measurements confirmed that recombinant unhydroxylated fibrils presented a broad distribution with a minimum at 15 nm and a maximum at about 500 nm. In contrast, Het I showed the highest frequency of striated fibrils with a diameter of about 40 nm (Fig. 6G).