Currently trying to memorize the different amino acid structures for my own learning purposes.

I think I am confusing myself, and would like clarification to see if it matters where the NH and double bond are placed in these two structures that I drew.

I marked the right side as correct and the left side as the incorrect one, but suddenly I am thinking that where you place the double bond and NH don't matter as long its placed in either orientation of the structure it should be tryptophan right?

enter image description here



I re-drew the structure, but am still not clear about the so called "trivial" rotation mentioned, does the new picture reflect whether or orientation not mattering? I am still confused if I drew it correct.


Simply put, I took my chemistry classes a few years ago and don't remember if this changes the structure if I changed the position of the NH and double bonds, that is all, and would some clarification on it. enter image description here

  • 1
    $\begingroup$ Care to explain why that is the case?? Don't really understand why this question is so poorly received I am genuinely trying to learn about amino acids. $\endgroup$ – user3665690 Feb 3 at 21:14
  • $\begingroup$ Some suggestions about why this is being poorly received. 1) This qualifies as a "homework" question since it "addresses a basic biology concept that may seem trivial to biology professionals". For such questions, you are required to use the "homework" tag. 2) It is actually a (trivial) chemistry question in disguise, since you are just asking whether a chemical compound is still the same after rotating a bond. ——— Have another look at a correct structure for tryptophan — you have the placement of the aromatic ring and the nitrogen wrong. $\endgroup$ – tyersome Feb 3 at 21:29
  • 2
    $\begingroup$ But its not a homework question, how do you want me to prove this? I'm not taking any classes and am studying for the MCAT exam, I wanted to memorize the amino acids, but am confused if switching or rotating the orientation of the NH and double bond would make it a different molecule other than tryptophan $\endgroup$ – user3665690 Feb 3 at 21:31
  • 2
    $\begingroup$ I have looked at the structure beside what I drew at least 100 times over and I cannot spot the difference between what I drew (incorrectly) and the correct structure. If I were asking a homework question, how come I did not reference a problem or something, I'm not trying to pick this molecule out of a list or anything like that, it is for my own personal understanding, not a homework related question, not sure how you would like me to prove this. $\endgroup$ – user3665690 Feb 3 at 21:34
  • 1
    $\begingroup$ Refs for tryptophan tautomers: here. Fig 1 of here $\endgroup$ – user1136 Feb 5 at 13:49

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.