Page 137 - Biochemistry2 (08PB403)

Fructose Metabolism

• The major source of fructose is the disaccharide sucrose, which,
when cleaved in the intestine, releases fructose & glucose.

• Fructose is also found as a free monosaccharide in fruits, honey and
high-fructose corn syrup used to sweeten soft drinks.

• To enter metabolism, fructose must be first phosphorylated; this is
performed by hexokinase (low affinity to fructose; present in all
body cells; yields F-6-P) or mainly by fructokinase (high affinity to
fructose; present in the liver, yields F-1-P). Finally, both enzymes
produce glyceraldehyde-3-phosphate, which either enters
glycolysis or is mainly converted to glucose by gluconeogenesis.

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