User:Stephen Mills/Peptide tutorial 2

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Peptide 2:

Let's look at another dipeptide.

Identify each amino acid in this dipeptide.

Second Dipeptide

What is the short-hand notation for this dipeptide?

Identify which amino acid is at the N-terminus and which is at the C-terminus.

Identify the α carbons of each amino acid.

Identify the atoms involved in the peptide bond in this dipeptide.

Now, measure the distance between the α carbons.

To measure a distance, Double click on the first atom, then double click on the second atom. You may need to rotate the molecule a bit to see the distance well. Try it now.

Write down this distance and submit it to your instructor.


Now you are ready to work with oligopeptides, or polymers composed of 3-20 amino acid residues. These polymers are linear; that is, each amino acid is linked to it's neighbor in a head-to-tail fashion rather than forming branched chains. You will be observing a 5mer in this tutorial.

For this part, you may need to resize and move the molecule around. To remind you:
To Rotate: left drag
To Zoom: scroll button or shift + left drag
To Translate: ctrl + right drag (On a Mac, this doesn't work in FireFox, but does work in Safari).

Identify where Y and R are located in this oligopeptide.

Notice that the NH of Y is bonded to the carbonyl of R.

Also notice how the bulky side-chains point away from the backbone of the peptide.

Identify where C and D are located in this peptide.

Notice how Cysteine's thiol (SH) group points outward from the 5mer backbone at an angle that would allow for the stable formation of the disulfide bond.

Identify the remaining amino acid in this peptide.

Write down the short-hand notation for this pentapeptide, in the correct order from the N-terminus to the C-terminus and submit this to your instructor.

Last Part!!

Now a test peptide.

Identify the sequence of this peptide and submit the answer to your instructor.
You will probably need to move the molecule around and rotate it to see the whole structure.

When you write down the sequence in the one letter codes, it will spell out a question.

Submit the sequence of the peptide and the answer to the question

Congratulations! You have just finished the first Biochemistry Tutorial

Click here to go back to the main Tutorial page.

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Stephen Mills

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