# The number of branch points (a-1,6 glycosidic bonds) in amylopectin can be calculated using a…

The number of branch points
(_-1,6 glycosidic bonds) in amylopectin can be calculated using a chemical
modification protocol based on extensive methylation, followed by hydrolysis,
reduction, and acetylation. Because the hydrolysis products differ with regard
to the position of methyl and acetyl groups in the released glucose molecules,
it is possible to use this method to determine the number of _-1,6
glycosidic bonds and hence the number of branch points and nonreducing ends in
the sample.

a. Assuming methylation of glycogen
at all available OH groups converts them to OCH3 groups, label
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The number of branch points
(_-1,6 glycosidic bonds) in amylopectin can be calculated using a chemical
modification protocol based on extensive methylation, followed by hydrolysis,
reduction, and acetylation. Because the hydrolysis products differ with regard
to the position of methyl and acetyl groups in the released glucose molecules,
it is possible to use this method to determine the number of _-1,6
glycosidic bonds and hence the number of branch points and nonreducing ends in
the sample.

a. Assuming methylation of glycogen
at all available OH groups converts them to OCH3 groups, label the amylopectin
molecule that follows (which contains a single terminal _-1,6 glucose)
with the correct glucose residues (A, B, C, D) based on the glucose products
shown below the molecule. b. If a 0.5-g sample of amylopectin was found to have
25 mg of 2,3-dimethylglucose, calculate the ratio of glucose molecules with
_-1,4 glycosidic bonds compared to those with _-1,6 glycosidic bonds.
Show your work and include units. Note the molecular mass of a glucose residue
in glycogen is 162 g/mol, and the molecular mass of 2,3-dimethylglucose is 208
g/mol. c. Calculate the approximate number of nonreducing ends in this 0.5-g
sample of amylopectin

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