Altered isoenzyme patterns of liver α‐L‐fucosidase in cystic fibrosis

Abstract

The isoenzyme pattern of .alpha.-L-fucosidase was studed by isoelectric focusing in livers from 7 patients with cystic fibrosis and in normal and pathological (GM1-gangliosidosis, Type II and Sanfilippo disease) controls. The controls had very reproducible patterns consisting of 7 isoenzymes of .alpha.-L-fucosidase with the most neutral form representing a small proportion of the total activity. All 7 of the cystic fibrosis livers had altered .alpha.-L-fucosidase isoenzyme patterns. The chemical relationship of the 7 isoenzymes of normal liver .alpha.-L-fucosidase was investigated using neuraminidase. The 5 most acidic forms of .alpha.-L-fucosidase appear to be related to the most neutral form by sialic acid residues. Since the isoenzymes of liver .alpha.-L-fucosidase appear to be related by sialic acid residues, it is possible that the altered .alpha.-L-fucosidase isoenzyme patterns found in cystic fibrosis livers may result from aberrant sialylation.