Palindromic Polypeptides

[Kam3725]

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Are palindromic peptides considered unique or the same? For example, would Gly-Gly-Gly-Ser be considered the same molecule as Ser-Gly-Gly-Gly or would they be classified as two different polypeptides?

 

[whiteshadodw]

Are palindromic peptides considered unique or the same? For example, would Gly-Gly-Gly-Ser be considered the same molecule as Ser-Gly-Gly-Gly or would they be classified as two different polypeptides?

nucleic acids and peptides have polarities, meaning, just as there is 5'-3' in DNA, there is N terminal to C terminal in peptides. thus, the palindromic amino acid sequences are not the same.

 

[Lexicon0]

I believe (not 100% sure) they would be considered unique due to directionality -

Eg: If you have (N-terminus)-Gly-Gly-Gly-Ser-(C-terminus) it would be different from (N-terminus)-Ser-Gly-Gly-Gly-(C-terminus).

Edit: Whiteshadow beat me to it!

 

[Kam3725]

I believe (not 100% sure) they would be considered unique due to directionality -

Eg: If you have (N-terminus)-Gly-Gly-Gly-Ser-(C-terminus) it would be different from (N-terminus)-Ser-Gly-Gly-Gly-(C-terminus).

Edit: Whiteshadow beat me to it!

Thanks!

 

[deleted329605]

I think first of all, you'd never have an amino acid chain that short. Secondly, I think if it was something like you have, the fold would indeed be very very similar giving rise to two oligopeptide chains that would have a relatively similar shape.

But yea, remember palindromes are definitely important when considering DNA in terms of restriction enzymes finding the correct sequence to cleave.

That's the only case I can remember palindromic things being important, any one have any?!!?

 

[Lexicon0]

I think first of all, you'd never have an amino acid chain that short. Secondly, I think if it was something like you have, the fold would indeed be very very similar giving rise to two oligopeptide chains that would have a relatively similar shape.

But yea, remember palindromes are definitely important when considering DNA in terms of restriction enzymes finding the correct sequence to cleave.

That's the only case I can remember palindromic things being important, any one have any?!!?

It's been a while since I've taken genetics, but I also remember palindromic sequences being important in transposons and conjugation? I'm pretty sure that all this is way beyond the scope of the mcat though..

 

[dmission]

It's been a while since I've taken genetics, but I also remember palindromic sequences being important in transposons and conjugation? I'm pretty sure that all this is way beyond the scope of the mcat though..

If I'm remembering correctly, I think that's for DNA, not proteins/amino acids

 

[whiteshadodw]

I think first of all, you'd never have an amino acid chain that short. Secondly, I think if it was something like you have, the fold would indeed be very very similar giving rise to two oligopeptide chains that would have a relatively similar shape.

But yea, remember palindromes are definitely important when considering DNA in terms of restriction enzymes finding the correct sequence to cleave.

That's the only case I can remember palindromic things being important, any one have any?!!?

not to be an ass, but just because you can't think of it doesn't mean it doesn't happen and doesn't mean its not important. and you can have peptide sequences as short as 2 amino acids, ever heard of solid-phase synthesis? there are palindromic sequences in proteins, and you can certainly have multiple applications of short palindromic sequences. you can pubmed palindromic protein and find tons of examples, i'll leave that to you. science is a huge, wide, and open field, don't be too narrow minded.

 

[Lexicon0]

If I'm remembering correctly, I think that's for DNA, not proteins/amino acids

Ah yes. That's what I meant but forgot to specify in my post.

 

[deleted329605]

not to be an ass, but just because you can't think of it doesn't mean it doesn't happen and doesn't mean its not important. and you can have peptide sequences as short as 2 amino acids, ever heard of solid-phase synthesis? there are palindromic sequences in proteins, and you can certainly have multiple applications of short palindromic sequences. you can pubmed palindromic protein and find tons of examples, i'll leave that to you. science is a huge, wide, and open field, don't be too narrow minded.

It funny when people say they don't mean to be an ass, the next thing out is just that. Well not to be an ass but, did you not see the part in my post where I asked if anyone knew of other cases where palindromes came into play!? Work on those verbal skills my friend, it's a third of the mcat.

 

[Calvinball]

I think first of all, you'd never have an amino acid chain that short. Secondly, I think if it was something like you have, the fold would indeed be very very similar giving rise to two oligopeptide chains that would have a relatively similar shape.

But yea, remember palindromes are definitely important when considering DNA in terms of restriction enzymes finding the correct sequence to cleave.

That's the only case I can remember palindromic things being important, any one have any?!!?

Dealing with peptides this short is the basis for protein sequencing.

Also, it's important to remember that when talking about restriction sites, a Palindrome does not have the same meaning as it does in literature, i.e. "it's the same backwards as it is forwards." Rather, the 5' to 3' read of that small segment is the same on the positive and negative strands.

Going back the the original question, both protein and DNA have directionality, which means that gly-ser-leu will not be the same as leu-ser-gly. And unless otherwise stated, it's safe to assume that DNA is listed 5' to 3', and protein is listed N-terminal to C-terminal.


One more thing Zwander, before attacking someone else's verbal skills, you may want to check to make sure your post doesn't begin with:

It funny when people say....