“…Major MS2 fragments of acyl-surugamide A2, their predicted fragment sequence, the equivalent fragment mass for surugamide A [1,21], and the mass difference of the fragments. The biosynthetic gene cluster of a NRP can also be used to determine the amino acid order of cyclic-NRPs [1,5]. To date, all core surugamides follow the LDLDLLDD amino acid configuration sequence [1][2][3]5,29] as well as the core AA order cyclo-[IAIIKIFL] with possible substitutions of L-Ile-1, L-Ile-2, or L-Ile-4 for Val [1,3,14].…”