1 endorphin

1 polypeptide, chain of amino acids linked by peptide bonds CO-NH, a component of protein

1 peptide (two or more amino acids linked by peptide bonds CO-NH)

1 peptidoglycan (PG) or murein (polymer of sugars and amino acids forming cell wall)

1 peptide bond CO-NH

2 bond in protein between carboxyl radical and amino radical