Figure 4. Effects of partial denaturation of the SP-A collagen-like domain on the ability of SP-A to induce Re-LPS aggregation.

In the left panel, SP-A-induced Re-LPS aggregation is shown as described in the text, but SP-A was preheated at the indicated temperatures before being added to the sample cuvette (10 μg/ml). After a 10 min equilibration at 37 °C, Ca²⁺ (2.5 mM) was added to the sample and reference cuvettes, and the change in absorbance at 400 nm was monitored. In the right panel, unfolding and refolding curves of human SP-A are shown. F was calculated as described in the Experimental section. The results shown are from a representative experiment of three experiments performed.