Number of Alanine molecules

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Number of Alanine molecules

Post by Purplez » Mon Sep 18, 2006 9:22 pm

Hi, I'm a little stumped on this question if you guys could help me out it would make my day :)

Assume that you have hydrolyzed 7mg of a polypeptide solution of a protein with a know molecular weight of 1265. You have also analyzed the type and quantity of amino acids.


alanine- Amount 0.97mg Molecular weight- 89
aspartic acid- Amount 2.19mg Molecular weight-133
cysteine- Amount 1.32mg Molecular weight- 120
glutamine- Amount 1.30mg Molecular weight-119
Serine- Amount 1.15 Molecular weight- 105

What is the number of alanine molecules in the polypeptide chain? This is a 3rd question after they asked the ratios of each amino acid to one another.

I just don't know how I should work the number out, thanks!

King Cobra
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Post by sdekivit » Tue Sep 19, 2006 6:28 am

you know the molar mass and the wiegth of the protein you analysed, thus you know the amount of molecules protein.

The same counts for alanine --> thus you can calculate the amount of molecules alanine in 1 molecule protein.

(Hint: you can also calculate the amount of mols alanine in 1 mol protein)

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