Question

Glycosidic linkage at the place of branching in starch and glycogen is
A. α1 → 6
B. α1 → 4
C. β1 → 4
D. β1 → 6

Answer 1

Hint: A glycosidic bond or a glycosidic linkage is formed between a hemiacetal or hemiketal group of any saccharide with the hydroxyl group of some other compound. A substance that contains a glycosidic bond is known as a glycoside.

Complete answer: The glycosidic bond is a bond when the carbohydrate compounds form a covalent bond with another functional group or compound. Starch and glycogen both are homopolysaccharides of glucose which form an α1 → 4 glycosidic linkage in the formation of linear polymer and α1 → 6 glycosidic linkage information of branching in the compound. A glycosidic linkage or a glycosidic bond is a kind of covalent bond which joins a carbohydrate molecule, mainly sugar, to another group, which can or cannot be another carbohydrate compound. An α-glycosidic bond is a bond that is formed when both the carbons have the same stereochemistry, while a β-glycosidic bond is a bond where the two carbons have different stereochemistry.
So, the right answer is option A.
Additional Information:
The word 'glycoside' is now also used to denote the compounds with bonds occurring between hemiacetal or hemiketal groups of sugars and other chemical groups. The compound R-OH in naturally occurring glycosides, in which the carbohydrate residue is removed is termed aglycone. Whereas the carbohydrate residue itself is often denoted as the 'glycine'.

Note: Glycoside hydrolases are also known as glycosidases are the enzymes that break the glycosidic bonds. Glycoside hydrolases usually act either on α- or on β-glycosidic bonds, but can’t act on both. Whereas the glycosyltransferases are the enzymes which transfer the sugar moiety from the activated donor to the accepting nucleophile in the acceptor substrate.