Hi,
I know in peptide bonds the amide group acts like a double bond and does not allow free rotation, but can this also be true for any amide bond? Is this just a property of amides in the peptide bond?
Thank you!!
Hey, some sources confuse the bonds and say it is flexible, because there are several attachment point to different atoms within the amide bonds, but as far as I know amide bond itself is planar and not so flexible.
An analogy to think about to make it clearer is that our forearm (jumping to Anatomy) is planar and not flexible, but the wrist and elbow joints are flexible (the atoms at the extremes which attach to other atom), yet the wrist and elbow have limitations because of the overall properties of your arm and forearm so they can’t really move in 360 and to any direction they want because of these limitations.
If amide bonds were not rigid and allowed for free rotation like a regular single bond, proteins would not be able to maintain their specific three-dimensional structures. This would prevent the formation of the various organization levels of proteins, such as the secondary structures (alpha helices and beta sheets) and the tertiary and quaternary structures. Without these organization levels, proteins would not be able to carry out their important biological functions.
The lack of free rotation around the amide bond is a general property of all amide bonds, not just those in peptide bonds. Amide bonds consist of a carbonyl group (C=O) and an amine group (NH2) and are formed through a dehydration reaction between these two functional groups. The resulting amide bond has partial double bond character due to resonance between the C=O and C-N bonds, which restricts rotation around the bond.
So, in summary, the lack of free rotation around the amide bond is a general property of all amide bonds, not just those in peptide bonds.
1 Like