| Revista: | Quimica nova |
| Base de datos: | PERIÓDICA |
| Número de sistema: | 000313443 |
| ISSN: | 0100-4042 |
| Autors: | Lima, Roberval Soares1 Nunes, Gilvanda Silva Noguer, Thierry2 Marty, Jean-Louis |
| Institucions: | 1Universidade Federal do Maranhao, Centro de Ciencias Exatas e Tecnologia, Sao Luis, Maranhao. Brasil 2Universite de Perpignan, Centre de Phytopharmacie, Perpignan, Pyrenees Orientales. Francia |
| Any: | 2007 |
| Període: | Feb |
| Volum: | 30 |
| Número: | 1 |
| Paginació: | 9-17 |
| País: | Brasil |
| Idioma: | Portugués |
| Tipo de documento: | Artículo |
| Enfoque: | Experimental, aplicado |
| Resumen en inglés | Initially, all major factors that affect the rate of the AldH-catalyzed reaction (enzyme concentration, substrate concentration, temperature and pH) were investigated. Optimal activity was observed between pH values of 7.5 and 9.5 in the temperature range of 25 to 50 ºC. Kinetic parameters, such as Km (2.92 µmol L-1) and Vmax (1.33 10-2 µmol min-1) demonstrate a strong enzyme-substrate affinity. The sensors were based on screen-printed electrodes modified with the Meldola Blue-Reinecke salt (MBRS) combination. Operational conditions (NAD+ and substrate contents, enzyme loading and response time) were optimized. Also, two enzyme immobilization procedures were tested: entrapment in poly(vinyl alcohol) bearing styrylpyridinium groups (PVA-SbQ) and crosslinking with glutaraldehyde. Chronoamperometry was employed to observe the biosensor responses during enzymatic hydrolysis of propionaldehyde and also to construct inhibition curves with maneb and zineb fungicides. Best results were found with the following conditions: [NAD+] = 0.25 mmol L-1; [propionaldehyde] = 80 µmol L-1; enzyme loading = 0.8 U per electrode; response time = 10 min, and inhibition time = 10 min. Current intensities around 103 ± 13 nA with the sensors and good stability was obtained for both immobilization procedures. Detection limits, calculated using 10% inhibition were 31.5 µg L-1 and 35 µg L-1 for maneb and zineb, respectively. Results obtained with other MBRS-modified electrodes consisting of mono and bi-enzymic sensors were compared. The ability to ca |
| Disciplines | Química |
| Paraules clau: | Química analítica, Fungicidas, Residuos de plaguicidas, Ditiocarbamatos, Aldehído deshidrogenasa, Biosensores, Cinética enzimática |
| Keyword: | Chemistry, Analytical chemistry, Fungicides, Pesticide residues, Dithiocarbamates, Aldehyde dehydrogenase, Biosensors, Enzymatic kinetics |
| Text complet: | Texto completo (Ver HTML) |
