Some physicochemical properties of human milk bile-salt activated lipase

Influence of pH, deoxycholate and denaturing reagents on human milk bile-salt activated lipase (EC 3.1.1.3) has been studied. It appears that pH between 5.0-8.0 has no significant effect on the secondary structure of this lipase, but its higher order structures are affected. Lipase-dependent 8-anilino-1-naphthalene sulphonate fluorescence has revealed that the deoxycholate activated form of lipase has a surface rich in hydrophobic amino acid residues. Circular dichroism and second derivative electronic absorption spectroscopic observations have also provided an evidence for deoxycholate-induced alterations in the surface conformation of this lipase.