Immobilized protein G is for binding the constant domains of immunoglobulin (Ig) molecules (see Figure 1). Protein G is a modified form of Streptococcal group G so that it does not bind to albumin. Protein G is coupled to 4% cross-linked agarose beads by a proprietary coupling method that provides high coupling efficiency for Ig and minimal protein G leaching. Our immobilized protein G has a high binding capacity (>20mg/ml resin).