Protein G Magnetic Beads are an affinity matrix for the small-scale isolation and purification of immunoglobulins. Specifically, the beads consist of a truncated form of recombinant Protein G that is covalently coupled to a nonporous superparamagnetic particle. The protein is coupled through a linkage that is stable and leak resistant over a wide pH range. Protein G exhibits high affinity for subclasses of IgG from many species including human, rabbit, mouse, rat and sheep.