Depletion of RuBisCO protein using the protamine sulfate precipitation method.

Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is a major high-abundant protein (HAP) in the plant leaves which hinders analysis of low-abundant proteins (LAP). In this chapter, we describe a highly simple RuBisCO depletion method using protamine sulfate (PS). Addition of 0.1 % PS is sufficient to precipitate the RuBisCO from the leaf extracts of diverse plants including monocots and dicots. Our results of SDS-PAGE, Western blotting, and two-dimensional gel electrophoresis showed that both large and small subunits of RuBisCO were precipitated in the pellet fractions, while LAPs were enriched in the supernatant fraction after PS precipitation.