Isopeptide bond

Isopeptide bonds are amide bonds formed between either a non-alpha carboxyl group with an alpha amino group or a non alpha amino group with an alpha carboxyl group in a polypeptide[1]. There are few enzymes that are able to hydrolyse Isopeptide bonds and therefore they are involved in the formation if dimers, multimers and complexes such as blood clots. Isopeptide bonds are the strongest bond in the quaternary structure of that can form within the cell as disulphide bonds can only form in the non-reducing enviroment outside the cell.