Pancreatic lipases: evolutionary intermediates in a positional change of catalytic carboxylates?

Comparison of the fold of lipases from Geotrichum candidum and from human pancreas identified a high degree of similarity which was not expected on the basis of their amino acid sequences. Although both enzymes utilize a serine protease-like catalytic triad, they differ in the topological position of the acid. We speculate that these proteins are evolutionarily related and that the pancreatic lipase is an evolutionary intermediate in the pathway of migration of the catalytic acid to a new position within the fold.