Acyl carrier protein (ACP), all abundant protein in every cell, plays a central role in a number of metabolic processes requiring acyl group transfer. Conformational flexibility While crucial for its function remains Substantially unaddressed. By dual polarization interferometry we establish correlation between the chain length of aliphatic groups covalently linked to Escherichia coli and Plasmodium falciparum ACP and their respective partial molar volumes in solution which helps to subserve the aforesaid goal. (C) 2009 Published by Elsevier Inc.