Selective Enrichment of Proteins Using Formed‐In‐Place Membranes

A process for selective enrichment of immunoglobulins has been developed using formed‐in‐place membranes on sintered stainless steel tubes. The process employs both size exclusion and protein charge manipulation around the isoelectric point of proteins to selectively reject or pass components of the stream. Volume recoveries of 95% (20X concentration) could be achieved with a single filtration without loss of fractionation capabilities. The large initial volume reduction allows for small subsequent diafiltration volumes and insures optimization of fractionation while minimizing total processing volume. The process has been used to enrich proteins representing a small percentage of the total protein from a large feed volume. As an example, immunoglobulin G (IgG) from cheese whey was enriched from 8% to 20% of total whey protein with a 90% recovery of the IgG.