Microfiltration Affinity Purification of Lactoferrin and Immunoglobulin G from Cheese Whey

A process combining affinity chromatography with membrane filtration was used to isolate lactoferrin and immunoglobulin G from Cheddar cheese whey. Heparin Sepharose, protein G Sepharose, and protein G bearing Streptococcal cells were used as adsorbents to form affinity complexes with target proteins. These could be retained by 0.2 μm microfiltration membranes and separated from unbound whey proteins. Binding capacities and binding constants of adsorbents determined by Langmuir‐type adsorption isotherms were 124 mg/mL gel and 5.4 × 10⁻⁶M for heparin Sepharose, 17.8 mg/mL gel and 3.5 × 10⁻⁷M for protein G Sepharose, and 148 μ.g/mL cell suspension and 1.1 × 10⁻⁷M for protein G cells. Lactoferrin with 95% purity and 92% iron‐binding capacity, and immunoglobulin G with 90% purity and 86% activity could be obtained with reasonable yields.