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The resulting C-N bond is called a peptide bond, and the resulting molecule is called an amide. Polypeptides and proteins are chains of amino acids held together by peptide bonds. The backbone of PNA is also held together by peptide bonds.

The C-N bond has a partial double bond character (with the Nitrogen atom attaining a partial positive charge and the oxygen atom a partial negative charge) and the molecule can normally not rotate around this bond. The whole arrangement of the four C,O,N,H atoms as well as the two attached carbons in a peptide bond is planar.

A peptide bond can be broken by amide hydrolysis (the adding of water). The peptide bonds in proteins are metastable, meaning that in the presence of water they will break spontaneously, releasing about 10 kJ/ mol of free energy, but this process is extremely slow. In living organisms, the process is facilitated by enzymeAn enzyme is a protein, or protein complex, that catalyzes a chemical reaction. Like any catalyst, enzymes work by lowering the activation energy of a reaction, thus allowing the reaction to proceed to its steady state or completion much faster than it ots. Living organisms also employ enzymes to form peptide bonds; this process requires free energy. The wavelengthThe wavelength is the distance between repeating units of a wave pattern. It is commonly designated by the greek letter lambda (λ). In a sine wave, the wavelength is the distance between peaks: The x axis represents distance, and I would be some va of absorbanceIn spectroscopy, the absorbance ''A is defined as : where I is the intensity of light at a specified wavelength that has passed through a sample and is the intensity of the light before it enters the sample. Absorbance measurements are often carried out i for a peptide bond is 220-280nm.