Altered isoenzyme patterns of liver alpha-L-fucosidase in cystic fibrosis.

The isoenzyme pattern of alpha-L-fucosidase was studied by isoelectric focusing in livers 
from seven 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 seven isoenzymes of alpha-L-fucosidase with the most 
neutral from (I) representing a small proportion of the total activity. 
All seven of the cystic fibrosis livers had altered alpha-L-fucosidase isoenzyme 
patterns. The chemical relationship of the seven isoenzymes of normal liver 
alpha-L-fucosidase was investigated using neuramindase. The five 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. 