Fig. 6.

Thermal unfolding of type III collagen from a patient with a Gly619Arg mutation in COL3A1. Skin fibroblasts were obtained from the patient and a control. The effect of a single base missense mutation was tested on the type III collagen protein by using a proteinase assay. The type III collagen was first digested with collagenase which cleaves the molecule at aa 781. This was then followed by digestion with trypsin and chymotrypsin. A large fraction of the patient’s type III collagen was digested to a fragment of approximately 620 aa at temperatures 20–36°C. In comparison the type III collagen isolated from control fibroblasts stayed intact and did not break down until at 38°C. Reproduced with permission from (Kontusaari et al., 1990b).