Purity ~95% (SDS-PAGE). Purified protein. Negative for HBsAG and HIV antibodies. Human type I collagen purified by serial salt precipitations, alcohol precipitation and DEAE chromatography of a pepsin extraction of human placenta. Composition: (a1(I))2, a2(I), native triple helix. Contaminants: >2% collagen type III, < 1% collagen type IV or collagen type V and < 0.5% non-collagen proteins