Reducing ends

Glycogen only has one reducing end and a large number of non-reducing ends with a free hydroxyl group at carbon 4. To be honest, I was never shown how to calculate this. Would you mind explaining it to me?

I had a substantial difficulty finding anything relevant to this online .There's a VERY brief sentence in my biochemistry book that says a glucose molecule with n branches will have n+1 non-reducing ends.


However, this is what I found somewhere else and is what I'm unsure about with it (I of course altered the original numbers from where I found it to my numbers):

 If there is one glucose substituent per branching point, the number of glucose molecules used for the substitution is found by iteration starting by 1000/10 = 100, but 900/10 = 90. Hence the average is where the ends meet: That is about 100+90/2 = 95 substituents (depending on how numbers are rounded up or down), which gives 95 non-reducing ends + 1 from the "backbone = 96.

The only thing about that method that I do not understand is the step of the 900/10=90 part; what does that tell us?

I asked my instructor he said I have the right idea for the beginning but that I may want to look at my work near the end, which i'm guessing is the dividing part or something.

Chances are your instructor doesn't know either. It's one of those mathematical problems that are useless to the field - simply testing your algebraic manipulation skills. As an instructor myself, I think it's useless. I think the 90 represents the branches.

So if the 90 represents the branches, is it possible then that there is 91 non-reducing ends?

I messaged the person that had posted what I quoted above and this is what they replied back with, maybe it will help...

"In the case of glycogen if we have three residues then there will be two bonds between them. So, if there are n number of sub-units, always the number of bonds will be n-1. So, we divide and substract one part from the wholesome glucose units. And from this remaining units you calculate the non reducing ends. Average is taken to know the how the ends meet."

If your glycogen subunit is made up of 1000 glucose units. You divide this number by 10, which will give you the number of branches -- 100. In each branch, there will be 1 non-reducing end, therefore 100 non-reducing ends. However, on the main branch, you have a reducing end and a non-reducing end. So it would be 101 non-reducing ends in total...

I'm not totally sure