The absorption spectrum bands of amide infrared radiation (IR), amide I (1600–1800 cm–1), amide II (1470–1570 cm–1), amide III (1250–1350 cm–1), and amide A (3300–3500 cm–1), are peaks of infrared characterization of amide. A protein peptide bond is an amide group.Apr 8, 2020