Metabolic labeling of glycosylphosphatidylinositol-anchor of heparan sulfate proteoglycans in rat ovarian granulosa cells

Isolation and purification of proteoglycans

Purification of a protein typically involves development of a quantitative assay to track protein integrity (e.g. enzyme activity) during subsequent isolation steps. The generalized procedure involves choosing the source of the protein, defining extraction conditions, developing bulk purification methods followed by refined, more selective methods. The purification of proteoglycans is often complicated by a) limited source quantities, b) necessity of chaotrophic solvents for efficient extraction, c) their large molecular size and d) lack of defined functions to enable purity (i.e. activity, conformation) to be assessed. Because the usual goal of proteoglycan purification is physical characterization (intact molecular weight, core protein and glycosaminoglycan class and size), the problems of a suitable assay and/or native conformation are avoided. The 'assay' for tracking proteoglycan isolation typically utilizes uronic acid content or radiolabel incorporation as a marker. Once extracted from their cellular/extracellular environment, proteoglycans can be isolated by density gradient centrifugation and/or column chromatography techniques. Recent advances in the composition of chromatographic supports have enabled the application of ion-exchange, gel permeation, hydrophobic interaction and affinity chromatography resins using efficient high-pressure liquid chromatography to proteoglycan purification.

Proteoglycans and hyaluronan in female reproductive organs

Proteoglycans and hyaluronan have been isolated from various female reproductive organs and fetal membranes. Special attention has been directed to changes in the composition of these molecules in the tissue during pregnancy and ovulation. Various chondroitin sulfate/dermatan sulfate proteoglycans, which represent extracellular matrix proteoglycans, are closely related to the organization of connective tissues. Heparan sulfate proteoglycans are widely distributed on the plasma membrane of most mammalian cells including those in the female reproductive organs. They are involved in various aspects of cell-to-cell or cell-to-extracellular matrix interactions. Although the precise biological functions of these proteoglycans are not currently clear, recent advances in biochemistry and molecular biology techniques promise an exciting new development in this area.

Isolation and purification of proteoglycans

Purification of a protein typically involves development of a quantitative assay to track protein integrity (e.g. enzyme activity) during subsequent isolation steps. The generalized procedure involves choosing the source of the protein, defining extraction conditions, developing bulk purification methods followed by refined, more selective methods. The purification of proteoglycans is often complicated by a) limited source quantities, b) necessity of chaotropic solvents for efficient extraction, c) their large molecular size and d) lack of defined functions to enable purity (i.e. activity, conformation) to be assessed. Because the usual goal of proteoglycan purification is physical characterization (intact molecular weight, core protein and glycosaminoglycan class and size), the problems of a suitable assay and/or native conformation are avoided. The 'assay' for tracking proteoglycan isolation typically utilizes uronic acid content or radiolabel incorporation as a marker. Once extracted from their cellular/extracellular environment, proteoglycans can be isolated by density gradient centrifugation and/or column chromatography techniques. Recent advances in the composition of chromatographic supports have enabled the application of ion-exchange, gel permeation, hydrophobic interaction and affinity chromatography resins using efficient high-pressure liquid chromatography to proteoglycan purification.