Tripeptides are composed of three amino acids linked by peptide bonds. Given a set of amino acids, you can make several different tripeptides.
a. Use the three-letter shorthand notations to name all the tripeptides that can be made from serine, tyrosine, and glycine. Each amino acid will be used once in each tripeptide.

Question

Tripeptides are composed of three amino acids linked by peptide bonds. Given a set of amino acids, you can make several different tripeptides.

a. Use the three-letter shorthand notations to name all the tripeptides that can be made from serine, tyrosine, and glycine. Each amino acid will be used once in each tripeptide.

Accepted Answer

Welcome back everybody. Our next problem says trip peptides consist of peptide bonds connecting three amino acids with a collection of amino acids. One can synthesize an array of tripeptide utilize the abbreviations consisting of three letters to identify every tripeptide that can be synthesized using tryptophan Prolene and Arginine. Each tripeptide will contain a single instance of each amino acid. We have four different answer choices with different possibilities using different abbreviations for amino acid. So before we even think about anything else, let's look at which abbreviations we use for these three amino acids. So Tryptophan has the three letter abbreviation of TRP. For Prolene, we use the three letter abbreviation Pr O, each of these abbreviations has a capital letter to start it and then two lowercase letters. And then for Ar Janine, we have a RG. So the first thing we should do is look at our answer choices and see. Do these the correct abbreviations. Choice. A tryptophan is correct. But for Prolene, they're using PLN. So that's incorrect. So choice A cannot be our answer choice. B uses TRP Pr Oarg. So nothing wrong with the abbreviations. So we'll leave that there. Choice C for tryptophan uses TYP. So that's an incorrect abbreviation for tryptophan and choice C is incorrect. And Choice D uses incorrect abbreviation for both tryptophan and Prolene using TYP and PLN. So choice D is incorrect. So without doing anything more, just by looking at the abbreviations, we have our correct answer of B just by process of elimination. Since this is a practice problem, we'll just delve into this just a little bit more thoroughly. So we recall that we have these polypeptides. So we start with the basic structure of an amino acid. For each one we have, we always start by convention with its amino group on the left. So the N terminus of the amino of the polypeptide chain will be first, then we have a carbon which we call our alpha carbon, which has a hydrogen and the R group that distinguishes the, I mean individual amino acids attached to it, then a carbon carbon and then hydroxy group. So we've got our amino group on one end, our carboxylic acid on the other with that alva alpha carbon bonded to the R group in the middle and to form polypeptides that reacts with a second amino acid. So we'll draw that one same structure but perhaps a different R group if it's a different ami amino acid. And that reaction involves elimination of a water molecule by removing the hydroxy group of the carboxylic acid of the first amino acid. And one of the hydrogens for the amino group of the second. So we end up with this reaction where we form a peptide bond by eliminating a water molecule. So we've eliminated water. And then I'm going to highlight in blue, you can see we have a new bond between the carbon carbon of our first amino acid and the nitrogen of the second. So that would be our peptide bond. And in these three letter abbreviation notations, we have hyphens in between each abbreviation and those hyphens represent the peptide bond between those amino acids. So our first amino acid on the left will be our N terminal amino acid. The last one on the right are C terminal. And when we think about the possible different arrangements of these three, we'd start with having Trypan first. So Trp Pr Oarg in the order we're giving them, we could also arrange that trparg pr O. So we've got two possible arrangements with tryptophan first. And we see that in choice B, if we put Prolene first, we could go Pr Otrparg or Pr Oarg trp. And we see those two represented next. And then finally, we could put a RG first and have a RG pr OTRP or a RGTRP pr O. And again, we see those represented in choice B, these are all the possible ways we can arrange these three if no one amino acid is represented more than once. So we've confirmed that indeed choice B is the correct representation of the all the possible tripeptide that can be synthesized using tryptophan prolene and arginine. See you in the next video.

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Key Concepts

Amino Acids

Peptide Bonds

Tripeptides