MPLA Synthetic Synthetic lipid A from E. coli (MPLAs) is a monophosphoryl lipid A with 6 fatty acyl groups. It is structurally very similar to natural MPLA except that natural MPLA contains a mixture of 5, 6, and 7 acyl lipid A. The number of fatty acids is a major determinant of the immunogenicity of endotoxin. Synthetic E. coli lipid A activates TLR4 but does not activate TLR2 even at high concentrations reflecting its high purity. CAS Number: 1246298-63-4 Formula: C96H184N3O22P Molecular weight: 1763.47 Endotoxin level: 1 x 10e6 EU/mg Solubility: 1 mg/ml in DMSO