Effect of β-Gal on incorporation / interaction with lipid bilayers (SUV): analytical ultracentrifugation(AUC) and dynamic light scattering (DLS) approaches.

PEDRO D. CLOP; MARIA A. PERILLO

Santiago del Estero

Congreso; XLIV Reunión Anual SAB 2015; 2015

Sociedad Aregentina de Biof{isica

β-galactosidase(β-Gal) is a glycosylhydrolase which hydrolyzes the β-glycosidic bond formed between a galactose and its organic moiety(aglycone). In our laboratory we are studying the modulation of the activity of β-Gal in heterogeneous systems, and we have shown that the interaction of this enzyme with lipid bilayers induce changes in the activity of the enzyme on soluble substrates, depending on the composition, the curvature, the molecular packing of the membrane, and consequently, the type of lipid-protein interaction (adsorption or penetration) that could be established.To understand the effects of incorporation/interaction of β-Gal with lipid bilayers, we use small unilamellar vesicles (SUV) from egg phosphatidylcholine (egg PC), a lipid that has no lateral segregation phase at the temperature studied. The β-Gal-SUVs interaction, was analyzed by analytical ultracentrifugation (UCA) and dynamic light scattering (DLS). Experimental data allowed us to determine the hydrodynamic parameters of pure β-Gal (sedimentation coefficient, S=15; Stokes radius R= 6.9nm and diffusion coefficient, D= 3.05 10-7 cm2/s) which resulted similar when mixed with SUVs, from which it could be inferred that UCA and DLS seem not to be able to resolve and/or stabilize β-Gal-SUV interaction in the conditions studied.