Agarose gel patterns of alkaline phosphatase isoenzymes before and after treatment with neuraminidase.

The clinical value of alkaline phosphatase isoenzyme analysis is limited by the inability of most electrophoretic methods to resolve the liver and bone isoenzymes. The authors attacked this problem by treating serum samples with neuraminidase, then running treated and untreated samples side-by-side on specially prepared agarose gels. Each isoenzyme showed a characteristic mobility before and after neuraminidase treatment that allowed its identification. The mobility of the bone isoenzyme was most affected, whereas the intestinal isoenzyme was resistant to the action of neuraminidase. In samples with both liver and bone isoenzymes, pretreatment with neuraminidase clearly distinguished the bands, allowing quantitation by densitometry. Using this method, the authors discovered 22 liver isoenzymes in 54 samples that were interpreted as only bone isoenzyme before neuraminidase treatment. They also detected two bone isoenzymes in 35 samples that appeared to contain only liver +/- biliary isoenzymes. In addition, this procedure enabled them to characterize several unusual isoenzymes with respect to mobility, thus avoiding confusion with the other isoenzymes.