Please can you clarify this for me, it drives me nuts ;-P
Forget about side chains and the H and just look at the amino group and carboxylgroup of AAs
H2N and COOH. Because one is a weak base and the other a weak acid, they act at physiolocal pH at proton acceptor/donor making it H3N+ and COO-, the usual zwitterionic form of AAs
( Hope I got it right so far)
Now in peptide bonds ( lets just look at the bonds and forget about the rest) the COOH forms with the next NH2 (of the next AA) a CONH +H2O bond
But you write a peptide bond starting with H3N.......
but where does the extra H come from? It could come from its own ( in zwitterionic form) , but then peptide bonds are not possible because the H from the COOH would be missing
Or do peptide bonds only happen well below pI?
Sorry if I ask such a basic question, but I look and search and cant find an answer.