Preparative separation of immunoglobulins from bovine colostrum by continuous divergent-flow electrophoresis

Area of Science:

• Biochemistry
• Analytical Chemistry
• Immunology

Background:

• Bovine colostrum is a rich source of immunoglobulins, crucial for passive immunity.
• Efficient separation of specific immunoglobulins from complex colostrum matrices remains a challenge.
• Existing methods often require extensive pre-preparation or lack preparative scale capabilities.

Purpose of the Study:

• To develop and validate a novel preparative method for isolating immunoglobulin G (IgG) from bovine colostrum.
• To characterize the separated IgG fractions using advanced electrophoretic techniques.
• To demonstrate the direct application of defatted, casein-free colostrum supernatant without further pre-treatment.

Main Methods:

• Bidirectional isotachophoresis/moving boundary electrophoresis coupled with electrofocusing in a pH gradient (3.9–10.1).
• Utilized preparative instrumentation with a trapezoidal non-woven fabric for continuous flow separation.
• Analyzed fractions using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and gel isoelectric focusing (gel IEF).

Main Results:

• Successfully fractionated immunoglobulin G from other major colostrum proteins, including bovine serum albumin and β-lactoglobulin.
• Detected IgG in seven distinct fractions collected over 3 hours, with decreasing concentrations.
• Isoelectric focusing revealed multiple IgG zones within fractions, spanning isoelectric point values from 5.4 to 7.2.

Conclusions:

• The developed bidirectional isotachophoresis/moving boundary electrophoresis method provides an effective means for preparative isolation of bovine IgG.
• The technique allows direct processing of colostrum supernatant, simplifying the separation workflow.
• Characterization confirms the purity and heterogeneity of the isolated immunoglobulin G fractions.