Characterisation of human lung elastin-derived peptides

The enzymatic breakdown of human lung elastin by leukocyte elastase precedes the development of pulmonary emphysema, and releases elastin-derived peptides (EDPs) into the circulation. While raised levels of EDPs measured by enzyme-linked immunosorbent assay (ELISA) have been proposed as a possible marker for early detection of emphysema, average normal values of EDPs measured by different investigators have differed by up to a factor of 1000. Standardisation of the methodology for elastin purification and EDP production in vitro is required to ensure the accuracy of EDP measurements in vivo, because antiserum used in the ELISA is raised against the EDPs produced in vitro. In the present study elastin was purified from human lung by sequential biochemical extraction, and solubilised by leukocyte elastase. Molecular weight distribution of EDPs produced by partial and complete elastin digestion were compared by gel exclusion chromatography. A method for successful separation of EDPs by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) is reported. The implications of these results for further immunological characterisation of these peptides are discussed with a view to standardisation of the techniques employed for the measurement of EDPs in vivo.