Hereditary Alterations of Fructose Metabolizing Enzymes

Two hereditary alterations of fructose metabolizing enzymes are known. We have shown that in essential fructosuria, there is in fact a deficiency of fructokinase activity. We have shown that in hereditary fructose intolerance (HFI) some abnormal properties of aldolase in liver are related to aldolases A (muscle type) and C (brain type) which are normally synthesized by embryo, and which persist without change. In livers with HFI, we have found a protein immunologically related to aldolase B (liver adult type), the enzymatic activity of which is about 3 per cent of the normal value. Its Michaelis constant for fructose‐1‐phosphate is greatly increased. We conclude that, in hereditary fructose intolerance, there is a mutation of the structural gene.