IIBYT   23944
INSTITUTO DE INVESTIGACIONES BIOLOGICAS Y TECNOLOGICAS
Unidad Ejecutora - UE
artículos
Título:
β-sheet to α-helix conversion and thermal stability of β-Galactosidase encapsulated in a nanoporous silica gel
Autor/es:
PERILLO, MARÍA A.; OCHOA, AYLEN; BURGOS, M. INES
Revista:
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
Editorial:
ACADEMIC PRESS INC ELSEVIER SCIENCE
Referencias:
Año: 2018 vol. 508 p. 270 - 274
ISSN:
0006-291X
Resumen:
The effect on protein conformation and thermal stability was studied for b-Galactosidase (b-Gal) encapsulated in the nanopores of a silicate matrix (Eb-Gal). Circular dichroism spectra showed that, compared with the enzyme in buffer (Sb-Gal), Eb-Gal exhibited a higher content of a-helix structure. Heating Eb-Gal up to 75 C caused a decrease in the content of b-sheet structure and additional augments on Eb-Gal components attributed to helical content, instead of the generalized loss of the ellipticity signal observed with Sb-Gal. Steady state fluorescence spectroscopy analysis evidenced an Eb-Gal structure less compact and more accessible to solvent and also less stable against temperature increase. While for Sb-Gal the denaturation midpoint (Tm) was 59 C, for Eb-Galit was 48 C. The enzymatic activity assays at increasing temperatures showed that in both conditions, the enzyme lost most of its hydrolytic activityagainst ONPG at temperatures above 65 C and Eb-Gal did it even at lower T values. Concluding, confinement in silica nanopores induced conformational changes on the tertiary/quaternary structure of Eb-Gal leading to the loss of thermal stability and enzymatic activity.