کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10605583 | 982733 | 2011 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Determination of the transgalactosylation activity of Aspergillus oryzae β-galactosidase: effect of pH, temperature, and galactose and glucose concentrations
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آلی
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Determination of the transgalactosylation activity of Aspergillus oryzae β-galactosidase: effect of pH, temperature, and galactose and glucose concentrations Determination of the transgalactosylation activity of Aspergillus oryzae β-galactosidase: effect of pH, temperature, and galactose and glucose concentrations](/preview/png/10605583.png)
چکیده انگلیسی
The catalytic potential of β-galactosidase is usually determined by its hydrolytic activity over natural or synthetic substrates. However, this method poorly predicts enzyme behavior when transglycosylation instead of hydrolysis is being performed. A system for determining the transgalactosylation activity of β-galactosidase from Aspergillus oryzae was developed, and its activity was determined under conditions for the synthesis of galacto-oligosaccharides and lactulose. Transgalactosylation activity increased with temperature up to 55 °C while the effect of pH was mild in the range from pH 2.5 to 5.5, decreasing at higher values. The effect of glucose and galactose on transgalactosylation activity was also assessed both in the reactions for the synthesis of galacto-oligosaccharides and lactulose and also in the reaction of hydrolysis of o-nitrophenyl β-d-galactopiranoside. Galactose was a competitive inhibitor and its effect was stronger in the reactions of transgalactosylation than in the reaction of hydrolysis. Glucose was a mild activator of β-galactosidase in the reaction of hydrolysis, but its mechanism of action was more complex in the reactions of transgalactosylation, having this positive effect only at low concentrations while acting as an inhibitor at high concentrations. This information is relevant to properly assess the effect of monosaccharides during the reactions of the synthesis of lactose-derived oligosaccharides, such as galacto-oligosaccharides and lactulose.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Carbohydrate Research - Volume 346, Issue 6, 1 May 2011, Pages 745-752
Journal: Carbohydrate Research - Volume 346, Issue 6, 1 May 2011, Pages 745-752
نویسندگان
Carlos Vera, Cecilia Guerrero, Andrés Illanes,