Soluble and fraction 1 protein in leaves of C3 and C4 grasses

The C4 grasses Cynodon dactylon L. Pers., Chloris gayana Kunth, Paspalum dilatatum Poir. and Pennisetum clandestinum Hochst. were analysed for their contents of protein, extracted by and soluble in neutral buffer solutions, and for the major soluble protein of the chloroplast, fraction 1 protein. Conditions avoiding oxidative changes were used. In the four C4 grasses, soluble protein was 26–30% of the total protein, and fraction 1 protein was 11–16% of the soluble protein. In three C3 grasses, soluble protein was 33–48% of total protein, and fraction 1 protein was 29–43% of soluble protein. The comparative solubilities and ease of extraction of C3 and C4 grasses is discussed in relation to nitrogen retention in grazing ruminants.