The different electrophoretic forms of post gamma-globulin their antigenic identity and their structural variability

Area of Science:

• Biochemistry
• Protein Chemistry
• Clinical Chemistry

Background:

• Post gamma-globulin is a protein component found in cerebrospinal fluid and urine, particularly in patients with tubular disorders.
• It has also been identified in other biological fluids, indicating broader physiological relevance.

Purpose of the Study:

• To investigate the heterogeneity of post gamma-globulin observed after storage.
• To characterize the different electrophoretic forms of post gamma-globulin and determine their molecular properties and N-terminal sequences.

Main Methods:

• Isolation of electrophoretic forms using gel chromatography, preparative continuous flow electrophoresis, and ion-exchange chromatography.
• Determination of molecular weight and N-terminal amino acid analysis for the isolated forms.

Main Results:

• Three immunochemically identical electrophoretic forms of post gamma-globulin were isolated.
• All forms had a molecular weight between 11,000 and 12,000.
• The N-terminal amino acids were Lys, Arg, and Leu, suggesting differences arise from the elimination of small basic peptides or amino acids from the N-terminus.

Conclusions:

• Post gamma-globulin exhibits heterogeneity, with distinct forms arising from post-translational modifications or degradation.
• The observed differences in N-terminal amino acids suggest a mechanism involving the removal of small peptides.
• Further research is needed to confirm the absence of enzymatic activity and fully elucidate the functional implications of these forms.