Banca de QUALIFICAÇÃO: PIETRA BRUNA BARBOSA BENTO

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : PIETRA BRUNA BARBOSA BENTO
DATA : 16/10/2024
HORA: 14:00
LOCAL: Presencial, Santo André, UFABC
TÍTULO:

Characterization and nano-immobilization of a novel thermophilic esterase belonging to the Thermotogaceae family with potential for biotechnological applications

PÁGINAS: 45
RESUMO:

Esterases are a class of enzymes that catalyze the hydrolysis of ester bonds, widely used in the food, pharmaceutical, and detergent industries. In this study, we present the isolation, biochemical and biophysical characterization, and nano-immobilization of a novel thermophilic esterase belonging to the Thermotogaceae family (named here Tbe). The three-dimensional structure of the Tbe, modeled using the AlphaFold program, exhibited a classical α/β-hydrolase fold formed by eight β-sheet strands in the core, with one buried α-helix and six others exposed to the solvent. Tbe was cloned, expressed in E. coli, and purified to near homogeneity using affinity chromatography and size exclusion chromatography. The secondary structure was analyzed by circular dichroism spectroscopy, revealing a predominantly α-helical secondary structure for recombinant Tbe, as suggested by molecular modeling. The melting temperature value determined for Tbe at pH 8 was of 78 ± 1°C, revealing the thermophilic behavior of the enzyme. Tbe was able to hydrolyze p-nitrophenyl acetate (pNPA), confirming its esterase activity, and reaching optimal activity at pH 8.0 and 50 ^oC. Also, in this study, we reported for the first time the successfully photochemical synthesis of stable and functional silver chloride nanoparticles (AgCl-NPs) stabilized and covered by Tbe (Tbe/AgCl-NPs). Tbe/AgCl-NPs were highly stable, with different shapes including spherical and cubic, crystalline in nature, and with diameter ranging from 20 to 200 nm. Moreover, the findings showed that the esterase activity of Tbe was maintained in the Tbe/AgCl-NPs. Finally, our results showed an increase in the thermostability of the Tbe when associated with the nanoparticles. The information described here should provide a useful basis for future research and biotechnological applications of nano-immobilized esterases.

MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1844792 - AMEDEA BAROZZI SEABRA
Membro Titular - Examinador(a) Interno ao Programa - 1762438 - JEAN JACQUES BONVENT
Membro Titular - Examinador(a) Externo à Instituição - KELLI CRISTINA FREITAS MARIANO
Membro Suplente - Examinador(a) Interno ao Programa - 3298754 - TALES ALEXANDRE DA COSTA E SILVA
Membro Suplente - Examinador(a) Externo à Instituição - RENAN DA SILVA NUNES