Immunochemical studies on dextrans: Microheterogeneity of dextran NRRL B1397 demonstrated by precipitation with concanavalin A

Dextran NRRL B1397 containing C-2 and C-3 branching points was fractionated by successive additions of concanavalin A (Con A). Quantitative experiments of the precipitations of the fractionates with Con A and homologous rabbit anti-dextran, and on inhibition of the precipitin reaction showed that the original dextran sample was composed of a heterogeneous population of dextran molecules. This heterogeneity was confirmed by methylation studies. The fractions were found to have almost the same contents of 1→3 branches but different contents of 1→2 branches. Fractions rich in 1→2 branches reacted well with both a homologous anti-dextran serum and Con A, whereas fractions poor in 1→2 branches either reacted little or not at all with the antiserum or Con A.