Avidin is a glycosylated polypeptide chain having a molecular mass of 68kDa and containing 4 subunits each with a binding site for biotin. The Avidin is purified by affinity chromatographic techniques. The purification procedure ensures minimal contamination by other proteins or DNA. The resulting high activity and purity of the product gives very low non-specific binding (NSB). Purity >92.0%.