Surface-induced aggregation of type I procollagen.
We have examined the state of aggregation of type I procollagen in the concentration range 5 to 800 micrograms/ml. Electron microscopy typically indicates a high proportion of aggregated material (greater than 50%), when a range of preparative techniques are used. Aggregates of in-register molecules (segment-long-spacing-like aggregates) are frequently observed, often with units of in-register molecules connected via the C-terminal propeptides. In contrast, studies using gel-filtration chromatography and density-gradient ultracentrifugation demonstrate only limited aggregation in solution (less than 5%) even at 800 micrograms/ml. The aggregated material is mainly dimeric and probably not segment-long-spacing-like. We conclude that aggregation of procollagen is strongly favoured by adsorption to a surface when samples are prepared for electron microscopy. The possible relevance of these observations to the fate of procollagen secreted by cells in vivo is discussed.
Mould
A P
AP
Department of Medical Biophysics, University of Manchester, England.
Hulmes
D J
DJ
D000818:Animals; D002499:Centrifugation, Density Gradient; D002642:Chick Embryo; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D011347:Procollagen; D013499:Surface Properties
D046911:Macromolecular Substances; D011347:Procollagen