Phosphopantetheine

4'-Phosphopantetheine is an essential prosthetic group of acyl carrier protein (ACP) and peptidyl carrier proteins (PCP) and aryl carrier proteins (ArCP) derived from Coenzyme A.

Functions
Phosphopantetheine fulfils two demands.
 * Firstly, the intermediates remain covalently linked to the synthases (or synthetases) in an energy-rich thiol ester linkage.
 * Secondly, the flexibility and length of phosphopantetheine chain (approximately 2 nm) allows the covalently tethered intermediates to have access to spatially distinct enzyme active sites.