Purification and characterization of type II collagen from chick sternal cartilage

Type II collagen was purified from sternal cartilage of the chick using a combination of pepsin digestion, NaCl precipitation and DEAE-sepharose CL 6B ion exchange chromatography. Pepsin-solubilized type II collagen of higher stability can be obtained with the extraction time of 32 h, 0.5% pepsin concentration at 20 °C. The purified preparation showed a single peak on RP-HPLC and a single band (α-chain) and its dimers (β-chains) on SDS–PAGE with a subunit Mr of 110 kDa. The amino acid composition of the type II collagen derived from chick cartilage was closer to that of reference Sigma–Aldrich type II collagen which contains more imino acid. Analysis by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) revealed that type II collagen from chick sternal cartilage retains more intermolecular crosslinks during the purification process. Collagen purified from chick sternal cartilage was typical type II collagen and may find applications in functional foods.