RESUMO
The genes of endoglucanases EG2 (36.2 kDa) Penicillium verruculosum and LAM (30.8 kDa) Myceliophthora thermophila were cloned in P. verruculosum recombinant strain. New enzyme preparations with highly stable activity against ß-glucan and laminarin were obtained and investigated, homogeneous enzymes EG2 (EC 3.2.1.4) and LAM (EC 3.2.1.6) being purified and characterized. For ß-glucan, the EG2 Km value was found to be 10 times higher than that for LAM; however, EG2 demonstrated greater processivity due to its higher kcat. The pH and temperature optima of EG2 and LAM activity against barley ß-glucan overlapped and were 4.3-4.9 and 61-67°C, respectively, and EG2 appeared to be more stable than LAM. Oligosaccharides with degree of polymerization 2-10 were formed by hydrolysis of ß-glucan and laminarin by the studied enzymes. The recombinant enzyme preparations were faster and more effective in decreasing the reduced viscosity of wholegrain barley extract than some commercial enzyme preparations. Thus, the new enzyme preparations seem to be rather perspective as feed additives for degradation of non-starch polysaccharides in grain animal feed.
Assuntos
Celulase/metabolismo , Penicillium/enzimologia , Sordariales/enzimologia , Celulase/genética , Celulase/isolamento & purificação , Hidrólise , Cinética , Polissacarídeos/metabolismo , Especificidade por SubstratoRESUMO
Genes of ß-mannosidase 97 kDa, GH family 2 (bMann9), ß-mannanase 48 kDa, GH family 5 (bMan2), and α-galactosidase 60 kDa, GH family 27 (aGal1) encoding galactomannan-degrading glycoside hydrolases of Myceliophthora thermophila C1 were successfully cloned, and the recombinant enzymes were purified to homogeneity and characterized. bMann9 displays only exo-mannosidase activity, the K(m) and k(cat) values are 0.4 mM and 15 sec(-1) for p-nitrophenyl-ß-D-mannopyranoside, and the optimal pH and temperature are 5.3 and 40°C, respectively. bMann2 is active towards galactomannans (GM) of various structures. The K(m) and k(cat) values are 1.3 mg/ml and 67 sec(-1) for GM carob, and the optimal pH and temperature are 5.2 and 69°C, respectively. aGal1 is active towards p-nitrophenyl-α-D-galactopyranoside (PNPG) as well as GM of various structures. The K(m) and k(cat) values are 0.08 mM and 35 sec(-1) for PNPG, and the optimal pH and temperature are 5.0 and 60°C, respectively.
Assuntos
Proteínas Fúngicas/metabolismo , Glicosídeo Hidrolases/metabolismo , Sordariales/enzimologia , Sequência de Aminoácidos , Clonagem Molecular , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Glicosídeo Hidrolases/química , Glicosídeo Hidrolases/genética , Concentração de Íons de Hidrogênio , Cinética , Dados de Sequência Molecular , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Especificidade por Substrato , TemperaturaRESUMO
Two alpha-galactosidases were purified to homogeneity from the enzymatic complex of the mycelial fungus Penicillium canescens using chromatography on different sorbents. Substrate specificity, pH- and temperature optima of activity, stability under different pH and temperature conditions, and the influence of effectors on the catalytic properties of both enzymes were investigated. Genes aglA and aglC encoding alpha-galactosidases from P. canescens were isolated, and amino acid sequences of the proteins were predicted. In vitro feed testing (with soybean meal and soybean byproducts enriched with galactooligosaccharides as substrates) demonstrated that both alpha-galactosidases from P. canescens could be successfully used as feed additives. alpha-Galactosidase A belonging to the 27th glycosyl hydrolase family hydrolyzed galactopolysaccharides (galactomannans) and alpha-galactosidase C belonging to the 36th glycosyl hydrolase family hydrolyzed galactooligosaccharides (stachyose, raffinose, etc.) of soybean with good efficiency, thus improving the digestibility of fodder.
