Purity ≥ 99% by SDS-PAGE. Collagen is an inert, rigid protein found predominantly in skin, ligaments, bones and teeth. Its most distinctive attribute, essential to a transmitter of mechanical force, is inelasticity. Its fundamental structural unit is tropo-collagen, a molecular rod about 2600A in length and 15A in diameter and 300,000 molecular weight. In tendons these macromolecules, grouped as collagen fibrils, run parallel to the axis. In skin the fibrils are interlaced and branched. FITC-labeled bovine type II is an excellent substrate for examining collagenase activity. This labeled substrate is highly purified and telo-peptide free and is supplied lyophilized or in solution. To minimize background levels in collagenase assays, FITC-labeled collagen has been enzymatically pre-treated and further purified by ion-exchange chromatography. FITC-labeled collagen can also be used as a substrate for cell culture. Collagen degradation products in the culture supernatants can be directly d