二氨基庚二酸（DAP)是一种氨基酸。它是赖氨酸的ε-羧基衍生物。

二氨基庚二酸是某些原核生物的细胞壁的组成成分。在构成革兰氏阴性菌的细胞壁的肽聚糖链上常常可以发现它的踪影。革兰氏阴性菌在有DAP供应时可以正常生长。在DAP缺乏的时候，它们仍然可以生长，但不能再合成构成细胞壁的肽聚糖。

DAP亦可构成博朗脂蛋白的连接点。

Diaminopimelic acid (DAP) is an amino acid, representing an epsilon-carboxy derivative of lysine.

DAP is a characteristic of certain cell walls of some bacteria. DAP is often found in the peptide linkages of NAM-NAG chains that make up the cell wall of gram-negative bacteria. When provided, they exhibit normal growth. When in deficiency, they still grow but with the inability to make new cell wall proteoglycan.