Reversed-phase liquid chromatography of elastin peptides

Soluble fragments of elastin are frequently present in biological tissue in small amounts. Because of their hydrophobic character, these peptides are not well resolved by a number of conventional techniques. However, their separation should be possible by reversed-phase chromatography. A wide range of columns, gradients and solvents were evaluated. Two systems are described. One was a C18 liganded silica column eluted isocratically by gravity flow. Some degree of size fractionation was achieved with larger peptides being eluted with methanol and smaller ones with isopropanol. The second system uses a pressurized elution from another C18 ligand column. A concave gradient of trifluoroacetic acid-acetonitrile with a decreasing acetonitrile concentration was optimal. Similar resolution of peptides produced by a variety of digestion methods was obtained with the lower-molecular-mass peptides eluting in the middle of the gradient.