in disaccharides we study maltose lactose lactulose and sucrose, their stuctures and their nuitritional role in human health

1. DISACCHARIDES

2. DISACCHARIDES
• Sugars composed of two mono saccharide units
joined by α -Glycosidic bond.
• MALTOSE14
• SUCROSE 12
• LACTOSE 14
• LACTULOSE14
• TREHALOSE11

3. MALTOSE

4. • COMPOSITION
• O α- D- Glucopyranosyl (1-4) α-D- Glucopyranosyl
• MALT sugar
• SOURCES
• Malt, germinating cereals, enzymatic hydrolysis of
starch by salivary & pancreatic Amylases.
• Maltase enzyme hdrolyzes Maltose into Glucose.
• strong reducing agent.
• Shows muta rotation.
• Forms sun flower shaped Osazone crystals.

6. ISOMALTOSE
• Enzymatic hydrolysis of branch points of the
AMYLOPECTIN unit of Starch.
• Shows α-(1-6) linkage.

7. LACTOSE
• SOURCES
• Milk ,pharmaceutical preparations.
• COMPOSITION
• O-β -D- Galactopyranosyl (1-4)-β- D- Glucopyranosyl
• Synthesized in mammary glands ,can appear in the
urine of lactating mothers.---LACTOSURIA.
• COW S’ milk contains 45% Lactose.
• Human milk contains 74% Lactose.
• Reducing sugar ,shows muta rotation.

9. LACTOSE INTOLERANCE
• Lactase deficiency
• Diarrhea ,flatulence , dehydration .
• Treatment
• Stop breast feeding/ milk intake.
• Yoghurt ,cheese & green vegetables for Ca++ intake.
• Lactase pills.

12. LACTULOSE
• O-α –D Galactopyranosyl (1-4 )-β-D Fructopyranosyl
•SOURCES
• Heated Milk , synthetically produced .
• Can not be hydrolyzed by intestinal enzymes .
• Fermentation by intestinal bacteria .
•USES
• Mild Diuretic /osmotic laxative .

13. SUCROSE (TABLE SUGAR )
• O α -D –Glucopyranosyl (1-2) β- D- fructofuranose
sources
• Cane ,beetroot,sorgham,fruits & vegetables.
• Non reducing sugar ,
• Does not form Osazone crystals.
• Does not exhibit muta rotation .
• Dextro rotatory sugar ( + 66.5 )
• On hydrolysis it becomes strongly Levorotatory (- 28.2)

15. • INVERT SUGAR
• Hydrolytic products of Sucrose are called invert sugars.
• Sucrose hydrolysis by Sucrase/ dilute acids liberates one
molecule each of α D- Glucopyranose & β –D
Fructofuranose.
• β D- Fructofuranose form is unstable & immediately gets
converted to β –D Fructopyranose form, which is
strongly Levorotatory ( -92 )
• Overall effect is INVERSION of dextro rotatory Sucrose
(+66.5) to Levorotatory.( - 22.8)
• Invert sugars are 33% more sweet than Sucrose i.e. Honey

16. TREHALOSE
• O α-D Glucopyranosyl (1-1) α-D Glucopyranosyl
• SOURCES
• Fungi, yeast

17. OLIGO SACCHARIDES
• 3-10 carbohydrate units.
• Components of integral membrane proteins,
present on their extra cellular domain.
• Mostly contain Mannose /Sialic acid residues.
• Help in degradation of these integral proteins.
• EXAMPLES
• Glycoproteins
• Antibodies
• Coagulation factors

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