Human brain aldolase C4 isoenzyme: purification, radioimmunoassay, and distribution in human tissues

The nervous system specific isoenzyme of frustose-1, 6-diphosphate aldolase (E.C.4.1.2.13), aldolase C4, has been purified from human brain, and a sensitive radioimmunoassay has been developed for its detection. This assay is also capable of detecting other hybrid isoenzymes containing the C subunit but not the A4 isoenzyme. A systematic survey of human organs has shown that immunoreactive aldolase C is present in all human organs but at levels less than 2% of those found in human brain; especially low levels occur in kidney, skeletal muscle, lung, and thyroid tissue. The presence of aldolase C in other organs apart from nervous tissue is unlikely to be explicable by innervation alone since significant quantities are found in erythrocytes. The high degrees of localisation of aldolase C4 in nervous tissue makes it a suitable marker for cell damage within the central nervous system.