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Food Technology and Biotechnology, Vol. 46 No. 3, 2008.

Original scientific paper

Transgalactosylation/Hydrolysis Ratios of Various β-Galactosidases Catalyzing Alkyl-β-Galactoside Synthesis in Single-Phased Alcohol Media

Irina Mladenoska orcid id orcid.org/0000-0003-3274-9158 ; Ss. Cyril and Methodius University, Faculty of Technology and Metallurgy, Department of Biotechnology and Food Technology, Rudjer Boskovic 16,MK-1000 Skopje, Republic of Macedonia
Eleonora Winkelhausen ; Ss. Cyril and Methodius University, Faculty of Technology and Metallurgy, Department of Biotechnology and Food Technology, Rudjer Boskovic 16,MK-1000 Skopje, Republic of Macedonia
Slobodanka Kuzmanova ; Ss. Cyril and Methodius University, Faculty of Technology and Metallurgy, Department of Biotechnology and Food Technology, Rudjer Boskovic 16,MK-1000 Skopje, Republic of Macedonia

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Abstract

Three microbial galactosidases, Aspergillus oryzae, Escherichia coli and Kluyveromyces marxianus β-galactosidase, were used as catalysts for transgalactosylation synthesis of alkyl-β-galactosides in single-phased alcohol media. Their selectivity towards different alcohol nucleophiles was quantified by determining the transgalactosylation/hydrolysis ratio in the water/alcohol mixtures containing water in concentrations below the level of saturation. p-Nitrophenyl-β-galactoside was used as a glycosyl donor at a concentration of 10 mM. Both the total reaction rate (transgalactosylation+hydrolysis) and the ratio between the transgalactosylation (alcoholysis) and hydrolysis increased with the increase of water activity. Although the A. oryzae β-galactosidase showed relatively low total activity (3.13 μmol/(min·mg protein)), it exhibited the highest selectivity towards the hexanol nucleophile among the examined enzymes (0.65). The selectivity values in all the examined cases were below one, which implies that the hydrolysis, and not the synthesis, was the dominating reaction. The total reaction rate (transgalactosylation+hydrolysis) was strongly affected by the water activity, and for the specific water activity in the different alcohols, it increased in the following order: n-octanol, n-hexanol, n-butanol.

Keywords

transgalactosylation/hydrolysis ratios; β-galactosidases; alkyl-β-galactoside synthesis; single-phased media; selectivity factors

Hrčak ID:

26382

URI

https://hrcak.srce.hr/26382

Publication date:

4.8.2008.

Article data in other languages: croatian

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