Phosphoglyceromutase activity and concentration in the endosperm of developing and germinating Ricinus communis seeds

Abstract

Monospecific antiserum was raised in rabbits to phosphoglyceromutase isolated from the developing endosperm of Ricinus communis. The antiserum binds to both the plastid and cytosolic isozymes of this enzyme. Both isozymes have a relative molecular mass of 64 500 and are monomers. The large increase in phosphoglyceromutase activity that occurs during seed development and early seedling growth coincides with an increase in the phosphoglyceromutase concentration. Contradictory results were obtained with the enzyme-linked immunosorbent and Western blot assays during the later stages of seed maturation and early stages of seed germination. This is probably a result of a heterogeneous mixture of phosphoglyceromutase fragments, resulting from partial proteolysis of the enzyme during the drying of the seeds.