Ox spleen ferritin: an isoelectrofocusing and crossed immunoelectrofocusing study.

Ox spleen ferritin was purified and its purity checked by two-dimensional immunoelectrophoresis and polyacrylamide plate electrophoresis. Microheterogeneity was shown with a preparation of purified ferritin by isoelectric focusing. The protein was separated into at least 6 fractions; two large fractions in the 4.50-4.55 pH range and another 4 in the 4.65-4.80 interval. Microheterogeneity was confirmed in purified preparations by crossed immunoelectrofocusing. Seven fractions were observed, the most acid ones (4.50-4.55) also being the most abundant. In the crossed IEF procedure, exactness in the isoelectrophoretic separation time is important in that excessive time may impair the resolution potential.