Composition comprising an enzyme having galactose oxidase activity and use thereof

[0066]A water soluble preparation of pentosans (WSP) was isolated from Thesee flour as described by Faurot et al., Lebensm.-Wiss. u-Technol. 28:436-444, 1995.

[0067]The WSP preparation was used as the source for isolating arabinogalactan, which in turn was used as substrate to determine the oxidizing activity of galactose oxidase. The WSP preparation can also be used as a source of arabinoxylan.

1.1. Purification of Arabinogalactan from Water Soluble Pentosans.

[0068]Reagents

[0069]Amyloglycosidase solution: 10 mg / ml amyloglycosidase (101332, Merck) was dissolved in 0.01 M acetate buffer, pH 5.0.

[0070]Pronase solution: 10 mg / ml pronase (165921, Boehringer Mannheim) was dissolved in 0.5 M phosphate buffer, pH 7.5.

[0071]Procedure

[0072]25 g WSP (Theses flour) was added to 880 ml Millipore water and pH was adjusted to 5.5. The resulting solution was stirred overnight. 10 ml of amyloglucosidase solution was added and the enzyme reaction was allowed to proceed for 2 hours at 40° C. under sti

Oxidation of Galactose-containing Compounds by Galactose Oxidase

[0094]Three different galactose-containing compounds were compared as substrates for galactose oxidase: (i) arabinogalactan treated with arabinofuranosidase, i.e. arabinogalactan with arabinose cleaved off, (ii) galactose and (iii) di-galactose. (FIG. 4). It can be seen that arabinose-free arabinogalactan was the most favourable of the tested substrates when compared on a galactose oxidase equivalent basis. Digalactose was oxidized nearly as good, but galactose was about three times less effective as substrate for galactose oxidase as compared to arabinofuranosidase treated arabinogalactan.

The Effect of Galactose Oxidase on Flour in a Model Dough System

3.1. Obtaining Purified Galactose Oxidase from a Crude Galactose Oxidase Preparation

[0095]A commercially available galactose oxidase preparation is the crude ferment of the enzyme from Sigma, catalogue No. G7400.

[0096]This preparation contains a mixture of enzyme activities and it was purified to ensure that any oxidative effect obtained was solely a result of galactose oxidase activity. G7400 is provided as an amount of lyophilized powder of a crude enzyme preparation containing a declared activity of 10,000 Sigma units. The preparation was purified in the following 3 steps:[0097]1) The 10,000 units of galactose oxidase was dissolved in 60 ml of water and filtered through a GP / B filter and subsequently through a 0.45 μm filter. This filtrate was applied to a 550 ml Sephadex G25 C desalting column (XK50, 5×28.5 cm). The column was equilibrated in 20 mm triethanolamine (TEA) buffer, pH 7.3 and eluted at a flow rate of 15