The low reactivity of peptide-prolyl-thioesters in native chemical ligation is not due to steric effects at the β-carbon, but rather to the presence of a carbonyl moiety on the nitrogen atom of the proline.
肽-脯
氨酰-
硫代酯在原生
化学连接中的低反应性并不是由于 β 碳的立体效应,而是由于脯
氨酸的氮原子上存在一个羰基。