Beta-Linked Disaccharides

lactose (milk sugar)
galactose-beta(1,4)-glucose

highlight the beta(1,4) glycosidic bond
highlight #4 hydroxyl at the non-reducing end


cellobiose
glucose-beta(1,4)-glucose

highlight the beta(1,4) glycosidic bond
highlight #4 hydroxyl at the non-reducing end

 
Lactose and cellobiose both have beta(1-4) glycosidic bonds.  The only difference between them is the chiral configuration at carbon #4 at the non-reducing end.  Lactose is also known as milk sugar.  The linkage  in lactose is one of the few beta-glycosides that can be digested by animals.  The inability to digest lactose by some adults causes lactose intolerance.  Cellobiose is a degredation product of cellulose.


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