alpha-peptide bond

[Elsha]

Hello,

 

does anybody know what alpha-peptide bond and alpha-amino group mean?

 

Thank you

[dttom]

The carbon adjacent to the carbon 1 is the alpha carbon.

[Elsha]

I know that the alpha carbon is the one linked to the radical specific for each amino acid. But what does alpha-peptide bond mean? In my book (harper's illustrated biochemistry) it says that ubiquitin is attached to lysyl residues in a given protein by NON-alpha peptide bonds. So if I don't know what alpha-peptide bond means I cannot understand ubiquitination.

 

Here are some thoughts (guesses): does non-alpha peptide bond mean that the bond is made between ubiquitin and an atom in the radical chain (as opposed to the chain common to all amino acids)?

[dttom]

A protein contains a series of peptide bonds which are alpha peptide bonds, as their linkage are made between alpha nitrogen and carbon 1. Lysine contains a side group with an amine functional group, which could form another type of peptide bond, such is not an alpha peptide bond as it is not adjacent to carbon one, it should be an epsilon peptide bond.

[Elsha]

Thank you, I understand better now. It's a shame those alpha and epsilon bond/atoms are nowhere explained... Not in my book, nor on the internet. While I understand epsilon (=sidechain?) and alpha, I just hope I won't come across more Greek letters ^^

[npts2020]

Cheer up, there are only 24 Greek letters.