An unusual buried polar cluster in a family of fungal lipases.

The stability of globular proteins arises largely from the burial of non-polar amino acids in their interior. These residues are efficiently packed to eliminate energetically unfavorable cavities. Contrary to these observations, high resolution X-ray crystallographic analyses of four homologous lipases from filamentous fungi reveal an alpha/beta fold which contains a buried conserved constellation of charged and polar side chains with associated cavities containing ordered water molecules. It is possible that this structural arrangement plays an important role in interfacial catalysis.