General Veterinary Biochemistry

PHYSIOLOGICALLY IMPORTANT MONOSACCHARIDES

Sugars	Occurrence	Functions
Pentoses
D-Ribose	Nucleic acids	As an important component of DNA, RNA and also in NAD+, NADP+, FAD +and ATP Ribose phosphates are intermediates in HMP pathway
D-Ribulose	Formed in metabolic processes	It is an intermediate in the HMP pathway
D-Arabinose	In wood gums	Constituent of glycoproteins
D-Xylose	Wood gums, proteoglycans and glycosaminoglycans	Constituent of glycoproteins
D-Lyxose	Heart muscle	A constituent of lyxoflavin isolated from human heart muscle
L- Xylulose	Intermediate in uronic acid pathway	-
Hexoses
D- Glucose(Blood sugar)	Fruit juice, hydrolysis of starch, cane sugar, maltose and lactose	The sugar of the body. The glucose is transported in the blood and oxidized in the cells to produce energy In diabetes the glucose is present in the urine
D-Fructose(Fruit sugar)	Found in fruit and honey	It is the sweetest of all the sugars. In seminal fluid it provides the energy source for the spermatozoa. It can be changed to glucose in the liver In some hereditary disorder fructose is accumulated causing hypoglycemia
D- Galactose(Brain sugar)	Hydrolysis of lactose	It can be changed to glucose in the liver. It is used to synthesize lactose in the mammary gland. A constituent of glycolipids and glycoproteins Failure in the metabolism leads to galactosemia and cataract
D-Mannose	Hydrolysis of plant mannans and gums	A constituent of many glycoproteins