THE MOLECULAR WEIGHT OF ANTIBODIES

Area of Science:

• Biochemistry
• Immunology
• Protein Chemistry

Background:

• Antibodies are crucial for immune response.
• Understanding antibody structure and stability is vital for their therapeutic and diagnostic applications.
• Previous methods for antibody purification sometimes altered their properties.

Purpose of the Study:

• To investigate the molecular characteristics of antibodies from different species.
• To assess the stability of antibodies under varying pH conditions.
• To determine if purification methods affect antibody integrity.

Main Methods:

• Salt dissociation for antibody purification.
• Ultracentrifugation to determine molecular weight and sedimentation.
• Analysis of frictional ratios to assess molecular shape.
• Activity assays and pH stability studies on horse antibodies.

Main Results:

• Salt dissociation effectively produced homogeneous antibodies without altering sedimentation.
• Antibodies from cows, horses, and pigs had a molecular weight of 990,000, while human, rabbit, and monkey antibodies matched normal gamma globulin.
• Both antibody types displayed non-compact or non-spherical shapes (frictional ratios 2.0 and 1.5).
• Horse antibodies remained stable between pH 3.44-9.06, with aggregation at lower pH and dissociation at higher pH.
• Extreme pH (1.44 and 12.4) led to molecular breakdown and activity loss.
• Prolonged immunization in horses sometimes resulted in antibody breakdown.

Conclusions:

• Salt dissociation is a suitable method for purifying homogeneous antibodies.
• Significant molecular weight differences exist in antibodies across species, influencing their structural properties.
• Antibody stability is pH-dependent, with specific ranges preserving activity and molecular integrity.
• Long-term immunization protocols may require careful monitoring to prevent antibody degradation.