Showell H J, Freer R J, Zigmond S H, Schiffmann E, Aswanikumar S, Corcoran B, Becker E L
J Exp Med. 1976 May 1;143(5):1154-69. doi: 10.1084/jem.143.5.1154.
24 di-, tri-, and tetrapeptides have been synthesized as a start of a systematic study of the structural requirements for chemotactic activity and lysosomal enzyme-releasing ability in rabbit neutrophils. All but two of them are N-formyl methionyl peptides. Using the method of Zigmond and Hirsch (10), two representative peptides, F-Met-Leu-Phe and F-Met-Met-Met, were shown to stimulate directed, as well as, random locomotion; thus, they were truly chemotactic. The various peptides showed a wide spread in activity. F-Met-Leu-Phe, the most active peptide studied, had an ED50 for induced migration of 7 X 10(-11) M and for lysozyme and beta-glucuronidase release of 2.4 X 10(-10) M and 2.6 X 10(-10) M, respectively; the least active, Met-Leu-Glu was 26 million times less active in these respects. The relation of activity to structure is exceedingly specific, very small changes in structure making large changes in activity. Moreover, this specificity exhibits a definite regularity and pattern; the activity of a given peptide depends not only on its constituent amino acids but on the position of the amino acid in the peptide chain. Most striking in this last regards is the high activity conferred by phenylalanine when it is in the carboxyl terminal position of a tripeptide, whereas, as the second amino acid from the NH2 terminal end whether in a tripeptide or a dipeptide, it contributes no more to the activity than other amino acids with hydrophobic side chains such as leucine or methionine. The high activity and the specificity and nature of the structural requirements strongly suggest that the primary interaction of peptide and neutrophil leading to either chemotaxis or lysosomal enzyme release is a binding of the peptide with a stereospecific receptor on the neutrophil surface. Whether all chemotactic factors act through the same receptor is not known. An essentially exact correlation exists between the concentrations of the various synthetic peptides required to induce migration and their ability to induce release of lysozyme or beta-glucuronidase. This implies that these two neutrophil functions are triggered by teh same primary interaction; possibly, the binding of the peptides to the same putative receptor. A higher concentration of a given peptide is required to stimulate lysosomal enzyme release than a corresponding migratory response. A slightly but significantly higher concentration of peptide is required to induce beta-glucuronidase secretion than lysozyme release.
已合成了24种二肽、三肽和四肽，以此作为对兔中性粒细胞趋化活性和溶酶体酶释放能力的结构要求进行系统研究的开端。除了其中两种外，其余都是N-甲酰甲硫氨酰肽。采用齐格蒙德和赫希（10）的方法，发现两种代表性肽，F-甲硫氨酰-亮氨酰-苯丙氨酸和F-甲硫氨酰-甲硫氨酰-甲硫氨酰，既能刺激定向运动，也能刺激随机运动；因此，它们是真正的趋化剂。各种肽的活性差异很大。研究中活性最高的肽F-甲硫氨酰-亮氨酰-苯丙氨酸，诱导迁移的ED50为7×10⁻¹¹ M，诱导溶菌酶和β-葡萄糖醛酸酶释放的ED50分别为2.4×10⁻¹⁰ M和2.6×10⁻¹⁰ M；活性最低的甲硫氨酰-亮氨酰-谷氨酸在这些方面的活性要低2600万倍。活性与结构的关系极为特异，结构上的微小变化会导致活性上的巨大变化。此外，这种特异性呈现出一定的规律性和模式；给定肽的活性不仅取决于其组成氨基酸，还取决于氨基酸在肽链中的位置。在这最后一点上最引人注目的是，当苯丙氨酸位于三肽的羧基末端位置时，它能赋予高活性，而当它作为从氨基末端起的第二个氨基酸，无论是在三肽还是二肽中时，它对活性的贡献并不比其他具有疏水侧链的氨基酸（如亮氨酸或甲硫氨酸）更大。高活性以及结构要求的特异性和性质强烈表明，导致趋化作用或溶酶体酶释放的肽与中性粒细胞之间的主要相互作用是肽与中性粒细胞表面的立体特异性受体结合。是否所有趋化因子都通过同一受体起作用尚不清楚。诱导迁移所需的各种合成肽的浓度与其诱导溶菌酶或β-葡萄糖醛酸酶释放的能力之间存在基本精确的相关性。这意味着这两种中性粒细胞功能是由相同的主要相互作用触发的；可能是肽与同一假定受体的结合。刺激溶酶体酶释放所需的给定肽的浓度高于相应的迁移反应所需的浓度。诱导β-葡萄糖醛酸酶分泌所需的肽浓度略高于但显著高于诱导溶菌酶释放所需的浓度。
