Purification of human plasma fibronectin using immobilized gelatin

This protocol describes a method for purification of fibronectin (Fn) from human plasma based on a combination of gel filtration and affinity chromatography steps. Clarified plasma is first loaded onto a Sepharose CL-4B column and unbound material is sequentially purified on columns containing covalently coupled gelatin and Arg. The elution conditions are optimized to obtain a homogeneous preparation of Fn on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Although the Fn yield is expected to be lower than that obtained using other methods, affinity adsorbents based on gelatin and Arg and gentle elution steps offer advantages including a high purity of the preparation and a correctly folded protein. The preparation can be useful for interaction studies and analysis of biological and immunological activities of Fn.