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Characterization and biotechnological application of an acid α-galactosidase from Tachigali multijuga Benth. seeds

Author:
Fialho, Lilian da Silva, Guimaraes, Valeria Monteze, Callegari, Carina Marin, Reis, Angelica Pataro, Barbosa, Daianny Silveira, Borges, Eduardo Euclydes de Lima, Moreira, Maurilio Alves, Rezende, Sebastiao Tavares de
Source:
Phytochemistry 2008 v.69 no.14 pp. 2579-2585
ISSN:
0031-9422
Subject:
Tachigali, seeds, seed germination, alpha-galactosidase, enzyme activity, thermal stability, enzyme inhibition, metal ions, enzyme substrates, oligosaccharides, enzymatic hydrolysis, substrate specificity, soymilk, locust bean gum, guar gum
Abstract:
Tachigali multijuga Benth. seeds were found to contain protein (364 mg g-1 dwt), lipids (24 mg g-1 dwt), ash (35 mg g-1 dwt), and carbohydrates (577 mg g-1 dwt). Sucrose, raffinose, and stachyose concentrations were 8.3, 3.0, and 11.6 mg g-1 dwt, respectively. α-Galactosidase activity increased during seed germination and reached a maximum level at 108 h after seed imbibition. The α-galactosidase purified from germinating seeds had an Mr of 38,000 and maximal activity at pH 5.0-5.5 and 50 °C. The enzyme was stable at 35 °C and 40 °C, but lost 79% of its activity after 30 min at 50 °C. The activation energy (E(a)) values for p-nitrophenyl-α-d-galactopyranoside (pNPGal) and raffinose were 13.86 and 4.75 kcal mol-1, respectively. The K(m) values for pNPGal, melibiose, raffinose, and stachyose were 0.45, 5.37, 39.62 and 48.80 mM, respectively. The enzyme was sensitive to inhibition by HgCl2, SDS, AgNO3, CuSO4, and melibiose. d-Galactose was a competitive inhibitor (K(i) = 2.74 mM). In addition to its ability to hydrolyze raffinose and stachyose, the enzyme also hydrolyzed galactomannan.
Agid:
744225