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-mu-m 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 x 10(-6)M for heparin Sepharose, 17.8 mg/mL gel and 3.5 x 10(-7)M for protein G Sepharose, and 148-mu-g/mL cell suspension and 1.1 x 10(-7)M 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.