FIG 4.

The LipB reaction. The CoA-derived ACP prosthetic group is shown with the octanoate moiety in blue. AcpP (called AcpA in a few bacteria) is the protein moiety of ACP (ACP is defined as the species carrying the prosthetic group). B. subtilis LipM performs the same reaction via the same mechanism that utilizes a thioester-linked acyl-enzyme intermediate (Fig. 5). This is an unusual pathway in that one protein-bound prosthetic group, 4′-phosphopantheine, allows the synthesis of another, lipoic acid.