Combined alcian blue and silver staining of subnanogram quantities of proteoglycans and glycosaminoglycans in sodium dodecyl sulfate-polyacrylamide gels

Proteoglycans stain weakly in polyacrylamide gels by traditional protein stains such as coomassie brilliant blue or silver. In the present work preparations of large aggregating proteoglycan from human articular cartilage were used to evaluate a convenient staining method based on successive staining with alcian blue and neutral silver. The method is developed for sodium dodecyl sulfate-polyacrylamide gel electrophoresis; with ultrathin minigels in a semiautomated electrophoresis system, takes 1 1/2 h, and uses stable reagents. Preparations, electrophoresis, and staining of up to 24 samples can be completed within 2 1/2 h. The method has a detection limit of 0.04-1 ng proteoglycan and less than 0.5 ng of glycosaminoglycan. In addition the method can be adjusted for selective staining of proteoglycans and glycosaminoglycans.