I know that amylose and amylopectin are major constituents of starch. I also know the chemical structures of amylose and amylopectin. However, I want to determine how amylose and amylopectin bond together. I think that the OH from the amylose bonds with the HO of the amylopectin to form an oxygen bond and a water. Am I correct, or does the OH chain of amylose bond with the O chain of amylopectin?

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  • $\begingroup$ What are you talking about? They're two molecules. When and why would such polymerisation supposed to occur? $\endgroup$
    – Mithoron
    Aug 28, 2016 at 0:32
  • $\begingroup$ Starch is composed of amylopectin and amylose molecules bonded together. My question is how and where are they bonded together. Is it a dehydration synthesis with the OH and HO groups? $\endgroup$ Aug 28, 2016 at 0:35
  • $\begingroup$ Different molecules can't be connected with covalent bonds as they would become one molecule. If you have a sugar or mix of different sugar molecules, they're connected with hydrogen bonds. $\endgroup$
    – Mithoron
    Aug 28, 2016 at 0:40
  • $\begingroup$ Ok. Thank you. So where would be the hydrogen bond connecting these two molecules? Which two parts of the respective molecules would be connected with each other? $\endgroup$ Aug 28, 2016 at 3:30
  • $\begingroup$ I suggest h bonds will form in all different parts between hydroxy groups and ether groups and between hydroxy and hydroxy. Water will form a hydration shell and will therefore function as some sort of lose connector. $\endgroup$
    – AstronAUT
    Aug 29, 2016 at 2:58

1 Answer 1


Actually you were close, below I have tried to discuss how this occurs:

Glycosidic bonds between monosaccharide units are the basis for the formation of oligosaccharides and polysaccharides such as starch.

It is possible for a sugar hydroxyl group (ROH) bonded to the anomeric carbon (the anomeric carbon is the carbonyl carbon of the open chain form of the sugar and is the one that becomes a chiral centre in the cyclic form) to react with another hydroxyl (R’-OH) to form a glycosidic linkage (R’-OR).

(A glycosidic linkage is not an ether)

Glycosidic linkages can take various forms; the anomeric of one sugar can be bonded to any one of the -OH groups on a second sugar to form an alpha- (as in starch) or beta-glycosidic linkage.

An example of a glycosidic bond (showing formation of maltose):


C-1 of one glucose is linked by a glycosidic bond to the C-4 oxygen of the other glucose when an ⎯OH (alcohol) of one glucose molecule (right) condenses with the intramolecular hemiacetal of the other glucose molecule (left), with elimination of H2O and formation of a glycosidic bond.

The reversal of this reaction is hydrolysis—attack by H2O on the glycosidic bond. In animal digestion (first phase), it is aided by α (1,4)-glucan 4-glucanohydrolase (salivary α-amylase)

Here is another comparison of the α 1,4 glycosidic linkage and α1,6 glycosidic linkage:


Having discussed about the glycosidic bond, we can refer back to starch: Starch is composed of two components, α-amylose and amylopectin. α-Amylose is composed of linear chains of D-glucose in α (1,4) glycosidic linkages. The linear linkages in amylopectin are α (1,4), whereas the branch linkages are α (1,6) glycosidic bonds:



It is also possible for polysaccharide units to form hydrogen bond interactions between neighbouring units, although these are minor and serve to stabilise the helical structure of amylose chains (around up to 6 residues per turn) but the major bonds are glycosidic bonds

I am sure you now have a clue on how they are bonded. Hope this helps.


Biochemistry (Campbell and Farell)

Lehninger Principles of Biochemistry

Biochemistry (Grisham)


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