Hopefully a quick question for a bio chem newbie.

 

Which amino acid residues in a protein can engage in hydrogen bonding?

 

Is the question

 

Don't all amino acid residues still have a c=o in them, and therefore all should be able to hydrogen bond? Or is there an amino acid with some brand of weirdness I don't understand?

Its mainly the sidechain parts of an amino acid that will contribute in hydrogen bonds, look for the ones that have O o N at the end of their side chains

oh I agree, that is actually the second part of the question - what R groups can hydrogen bond). The first part is specifically asks which residues can.

 

I was thinking since they all have that c=o then they all must be able to, regardless of what R group they have.

Think about the secondary structures. First consider the polypeptide backbone, and then consider the side-chains.

 

In a beta-sheet you get hydrogen bonding whatever the R-group (except proline); and in alpha-helices you get hydrogen bonding all the way up the helix.

 

You need to ask yourself which amino acids can be H-bond acceptors/donors. E.g. Do any have nitrogen or oxygen in their R-groups? Find a table of the amino acids online and have a careful think about their groups. You might also want to consider Pi-orbital stacking in Phenylalanine/Tyrosine residues.

 

Hope this helps! Good luck.

You might also want to consider Pi-orbital stacking in Phenylalanine/Tyrosine residues.

 

That was good advice