Question

Amylopectin is
A) Soluble in \[{{H}_{2}}O\]and have \[\alpha -1-4\]and \[\alpha -1,6\]glycosidic bonds.
B) Insoluble in \[{{H}_{2}}O\]and have \[\alpha -1,4\]and \[\alpha -1,6\]glycosidic bonds.
C) Soluble in \[{{H}_{2}}O\] and have \[\alpha -1,6\]glycosidic bonds.
D) Soluble in \[{{H}_{2}}O\] and have \[\alpha -1,4\]glycosidic bonds.

Answer 1

Hint: Amylopectin is the polymer of several D-glucose molecules. It is one of the two major types of carbohydrates found in starch. It has many end points at which the enzymes can attach. Its solubility depends on this characteristic.

Complete answer:
Amylopectin is a branched-chain polysaccharide. It is composed of units of glucose linked by α-1, 4-glycosidic bonds but with α-1, 6-glycosidic bonds occasionally, which are responsible for branching. This means that the 1-carbon of a glucose subunit is linked via a glycosidic bond to the 4-carbon of the next glucose subunit. And it is made up of a polymer of alpha-glucose units. Starch has 80% of amylopectin. It is one of the two major types of carbohydrates found in the starch (the other one is amylose). When iodine is added to starch, due to the presence of amylopectin, it gives reddish-brown appearance. It dissolves in hot water and on cooling; it forms a starch gel or starch paste.

The amylopectin is water-soluble and is a highly branched carbohydrate. Its solubility is because of the many end points at which the enzymes can attach. This is why amylopectin is different from amylose. The other type of carbohydrate amylose is relatively not as soluble. The amylase has either few or no $\alpha (1\to6)$ bonds that occur every 24 to 30 glucose subunits. Thus, amylopectin can be hydrolyzed more readily, more soluble, and with lower density compared with amylase.

Hence, the correct answer is option (A).

Note: In animals, the amylopectin is similar in structure and composition. It occurs in glycogen regarded by others as animal starch. The glycogen is a complex carbohydrate similar to starch, that stores excess glucose. The amylopectin in animals is different from amylopectin. Because the plant amylopectin has more extensive branching, that occurs every 8 to 12 glucose units.