Role of the cofactor calcium in the activation of outer membrane phospholipase A

A study was conducted on the characterization of calcium binding to outer membrane phospholipase A (OMPLA), focusing on the role of Ca in the activation and dimerization processes of OMPLA. Results suggested the presence of two Ca binding sites per OMPLA molecule. These sites may contain at least one negatively charged carboxylate. The primary structure of OMPLA had 15 glutamic acid and 16 aspartic acid residues. These residues were found to be the most likely candidates for being calcium ligands.