The common bonds which form long chain proteins are called bonds

Hydrophobic and hydrophilic bond/interactions are common bond that forms long chains of proteins.

Some complex forms of proteins are made of subunits in which molecules bond together to form a larger unit. A good example is the blood protein hemoglobin. Hemoglobin consists of protein subunits known as the globin molecules. These subunits are folded chains of a large number of different amino acids which are known as polypeptides.