Purification and characterization of two cartilage-inducing factors from bovine demineralized bone.

TLDR

CIF‑A and CIF‑B were isolated from bovine demineralized bone by dissociative extraction, gel filtration, cation‑exchange chromatography, and reversed‑phase HPLC. The purified peptides, each ~26 kDa (dimeric under reducing conditions) and possessing similar but distinct amino‑acid compositions, induce embryonic rat mesenchymal cells to adopt cartilage morphology and synthesize cartilage‑specific proteoglycan and type II collagen at 1–10 ng/ml.

Abstract

Two naturally occurring peptides that induce chondrogenesis in culture have been purified to apparent homogeneity. These cartilage-inducing factors (CIF-A and CIF-B) were isolated from bovine demineralized bone by dissociative extraction, gel filtration, cation-exchange chromatography, and reversed-phase HPLC. CIF-A and CIF-B at concentrations of 1-10 ng/ml each induce embryonic rat mesenchymal cells in culture to assume a cartilage morphology and synthesize cartilage-specific proteoglycan and type II collagen. The amino acid compositions of CIF-A and CIF-B are similar but not identical. Both factors have an apparent Mr of 26,000, as determined by NaDodSO4/PAGE. In the presence of 2-mercaptoethanol, both are converted to species of about one-half that Mr, indicating that they are dimers of identical or very similar chains.