Improved agarose electrophoretic method for separating alkaline phosphatase isoenzymes in serum

Area of Science:

• Biochemistry
• Clinical Chemistry
• Enzymology

Background:

• Alkaline phosphatase (ALP) isoenzymes play crucial roles in various physiological and pathological processes.
• Accurate separation and identification of ALP isoenzymes are essential for diagnosing conditions like liver disease, bone disorders, and certain cancers.
• Existing methods for ALP isoenzyme separation, such as cellulose acetate electrophoresis, may lack the sensitivity or resolution required for complex clinical samples.

Purpose of the Study:

• To develop and validate a modified agarose electrophoretic system for high-resolution separation of alkaline phosphatase (ALP) isoenzymes.
• To assess the sensitivity and reproducibility of the new system compared to existing methods.
• To identify and characterize various ALP forms, including bone, liver, high-molecular-mass, and intestinal ALP, as well as aberrant forms.

Main Methods:

• Development of a modified agarose gel electrophoresis protocol optimized for ALP isoenzyme separation.
• Comparative analysis of the agarose system's sensitivity and reproducibility against cellulose acetate electrophoresis.
• Characterization of separated ALP fractions using neuraminidase treatment and immunological assays (polyclonal and monoclonal antibodies).

Main Results:

• The modified agarose system achieved high reproducibility in separating bone, liver, high-molecular-mass, and intestinal ALP isoenzymes.
• The agarose system demonstrated superior sensitivity in detecting high-molecular-mass ALP compared to cellulose acetate.
• The system successfully identified immunoglobulin-bound ALPs, ALP-lipoprotein-X complex, and transient hyperphosphatasemia-associated ALP fractions.
• An additional fraction of intestinal-type ALP, termed "intestinal variant," was detected in approximately 25% of samples, requiring specific antibody-based confirmation due to overlapping mobilities.

Conclusions:

• The modified agarose electrophoresis provides a robust and sensitive method for comprehensive ALP isoenzyme analysis.
• This technique aids in the detection of clinically relevant ALP variants and complexes.
• Specific antibody-based confirmation is recommended for accurate identification of the "intestinal variant" and certain immunoglobulin-bound ALP fractions due to electrophoretic mobility similarities.