Isolation and partial characterization of a high molecular weight anionic glycoconjugate from transforming growth factor-β treated bovine articular chondrocyte cultures

Abstract

A high molecular weight anionic glycoconjugate was isolated from the media of the transforming growth factor-β treated chondrocyte cultures by anion-exchange chromatography on DEAE–Sephacel and Mono Q columns and was partially characterized. This high molecular weight anionic glycoconjugate was not detected in the non-treated (control) cultures. Characterization studies showed that the glycoconjugate is a non-reducible, non-collagenous glycoprotein containing O-linked, N-linked, and sialic acid substituted carbohydrate units. The isolated glycoconjugate stained "blue" with Stains All and migrated as a single band on sodium dodecyl sulfate gradient gels (2.5–10% acrylamide – diallyl tartardiamide) at an estimated molecular weight of 540 000. Amino acid and amino sugar analyses showed that it is rich in aspartic acid – asparagine, glutamic acid – glutamine, alanine, proline, and glycine, and contains galactosamine and glucoasmine. This transforming growth factor-β inducible glycoprotein may be involved in cell differentiation and in the cartilage repair process. It may also be used as a marker to localize the biological activity of transforming growth factor-β in articular cartilage.Key words: transforming growth factor-β, chondrocytes, anionic glycoconjugate synthesis.