The peptide bond linking the amino acids is planar as a result of the partial double-bond character of the peptide bond, and the side chains of the amino acids are usually trans to the polypeptide backbone.

• 连接氨基酸的肽键是平面的,这是由于具有肽键的双键性质的结果,并且氨基酸的侧链通常处于多肽骨架的反式位置。