Artículos de revistas
Environmental topology and water availability modulates the catalytic activity of beta-Galactosidase entrapped in a nanosporous silicate matrix
Burgos, Martha Ines; Velasco, Manuel Isaac; Acosta, Rodolfo Héctor; Perillo, Maria Angelica; Environmental topology and water availability modulates the catalytic activity of beta-Galactosidase entrapped in a nanosporous silicate matrix; Nature Publishing Group; Scientific Reports; 6; ; 4-11-2016; 36593-36603
Burgos, Martha Ines
Velasco, Manuel Isaac
Acosta, Rodolfo Héctor
Perillo, Maria Angelica
In the present work we studied the catalytic activity of E. coli β-Gal confined in a nanoporous silicate matrix (Eβ-Gal) at different times after the beginning of the sol-gel polymerization process. Enzyme kinetic experiments with two substrates (ONPG and PNPG) that differed in the rate-limiting steps of the reaction mechanism for their β-Gal-catalyzed hydrolysis, measurements of transverse relaxation times (T2) of water protons through 1H-NMR, and scanning electron microscopy analysis of the gel nanostructure, were performed. In conjunction, results provided evidence that water availability is crucial for the modulation observed in the catalytic activity of β-Gal as long as water participate in the rate limiting step of the reaction (only with ONPG). In this case, a biphasic rate vs. substrate concentration was obtained exhibiting one phase with catalytic rate constant (kcA), similar to that observed in solution, and another phase with a higher and aging-dependent catalytic rate constant (kcB). More structured water populations (lower T2) correlates with higher catalytic rate constants (kcB). The T2-kcB negative correlation observed along the aging of gels within the 15-days period assayed reinforces the coupling between water structure and the hydrolysis catalysis inside gels.