Problem 13 - Biochemistry

Question

Glycogen contains an \(\alpha-1,6\) -glycosidic bond about once every 10 glucose residues, thereby creating a branch point and a corresponding non reducing end for the removal and addition of glucose molecules. If a glycogen particle contains a total of 50,000 glucose residues, how many nonreducing ends are most likely to be found: \(\sim 25,000\) ends, \(\sim 2,500\) ends, or \(\sim 250\) ends? Explain your answer.

Step-by-Step Solution

Answer

Answer: Approximately 2,500 nonreducing ends.

Step 1: Calculate the Number of Branches

We know that there is an α-1,6-glycosidic bond once every 10 glucose residues, which creates a branch point. To find the number of branches, we divide the total number of glucose residues (50,000) by the frequency of these bonds (10). Number of branches = \(\frac{50,000}{10}\) Number of branches = 5,000

Step 2: Choose the Correct Number of Nonreducing Ends

Now we have to determine the closest number of nonreducing ends in the given options that correlates with our calculated number of branches. The options are: 1. 25,000 ends 2. 2,500 ends 3. 250 ends With 5,000 branches, option 2, with approximately 2,500 nonreducing ends, is the closest. Although it is not exactly half of the number of branches, it is the closest option to half the branches. The reason the number of nonreducing ends is lower than half the branches is that some of the branches form linear chains of glucose residues without any further branches, while others branch out multiple times. The most likely number of nonreducing ends in the glycogen particle is thus approximately \(\sim 2,500\) ends.