Isolation and characterization of 15K noncollagenous protein from bovine periodontal ligament.

Abstract

In pursuit of the nature of noncollagenous proteins (NCP) and their biosynthesis in periodontal ligament (PDL), isolation, characterization and a short incubation study were made on the PDL of the bovine mandibular incisors. A sodium chloride extract from the PDL contained several noncollagenous protein components. Eliminating serum derived proteins by a cross-reaction with antibody against bovine serum proteins, a protein estimated to be 15K on 5-15% gradient NaDodSO4-gel was the major constituent in the extract. This protein was isolated by sequential chromatography using Sepharose CL-6B and Sephacryl S-200 under dissociative conditions (4M guanidium hydrochloride). A chemical analysis of the protein showed that it was rich in aspartic acid, glutamic acid, glycine, alanine, leucine and lysine, and contained 5% sugars. Antibody directed against the purified PDL 15K protein reacted with the 15K protein, but no cross-reaction was observed with other components from the bovine PDL. A biosynthetic study of the protein using a short incubation with 3H-leucine indicated that the PDL cells produced the 15K protein and secreted it into the medium.