The tripeptide Gly-Ala-Ser is made from glycine (75.07 g/mol), alanine (89.09 g/mol) and serine…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
The tripeptide Gly-Ala-Ser is made from glycine (), alanine () and serine (). Water is . Find the number of peptide bonds, the amount of water released for each mole of tripeptide, and the molar mass of the tripeptide.
Need a reminder? The key ideaShow
A peptide bond forms with the loss of one water. A chain of residues has bonds, and its molar mass is the sum of the free amino acids minus for each bond. In an α-helix there are 3.6 residues per turn and a rise of 0.15 nm per residue. The C=O of residue bonds to the N-H of residue . The number of sequences with repeats is divided by the factorial of each repeat.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Plan. Three residues have two bonds. Each bond releases one water.
Step 1. Bonds. peptide bonds.
Step 2. Water. mol of water for every mole of tripeptide.
Step 3. Mass. . Take away , which gives .
Answer: 2 bonds, 2 mol of water, and .
Check. The tripeptide is lighter than the three amino acids together, as it should be.
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