For the measurement of 1,3:1,6-beta-glucan and α-glucan in yeast preparations.
INTRODUCTION:
(1-3)-β-Glucans are widely distributed in Nature, especially in algae,
fungi and yeast, but also in higher plants. They serve a variety of
biological functions. They form the major structural components of
cell walls, they act as storage carbohydrates and they sometimes play
a protective role by forming at specific sites in response to particular
stimuli such as wounding.1 The significance of (1-3)-β-glucans in the
wine making industry is related to the presence in wine of a particular
high molecular weight (~ 800 Kd) β-glucan, produced by the fungus,
Botrytis cinerea (grey rot). This glucan is composed of a (1-3)-β-linked
D-glucan backbone to which single D-glucosyl residues are attached
β-(1-6) to every third main-chain residue. The β-glucan passes into
the must and, as the alcohol levels rise in the latter stages of wine
making, aggregation occurs leading to clarification and filtration
problems. β-Glucan levels as low as 10 mg/L can cause serious
filtration problems2. These problems can only be removed by the
addition of specific enzyme preparations active on this polysaccharide.
At present the only method for detecting this β-glucan in wine is the
use of a non-specific alcohol precipitation test. β-Glucans also have
medicinal implications and literature indicates that the potent antitumour
properties of polysaccharide fractions extracted from certain
strains of mushrooms, in particular Grifola frondosa (also known as
Maitake), can be attributed to linear 6-branched, 1,3-β-glucan.3-5
It has been claimed that yeast β-glucan substantially enhances the
function of the immune system by activating macrophages, one of the
primary defences of the immune system.
This booklet describes a method for the measurement of (1-3)
(1-6)-β-glucan in yeast and mushrooms. Work is continuing on
extraction and decolourisation procedures for the analysis of β-glucan
in wine.
KITS:
Kits suitable for carrying out 100 assays are available from Megazyme.
The kits contain the full assay method plus:
Bottle 1: exo-1,3-β-Glucanase (100 U/mL) plus β-Glucosidase
(20 U/mL) suspension, 2.0 mL.
Stable for > 4 years at 4°C.
Bottle 2: Amyloglucosidase (1630 U/mL) plus invertase
(500 U/mL) solution in 50 % v/v glycerol, 20 mL.
Stable for ~ 2 years at 4°C or > 4 years at -20°C.
Bottle 3: GOPOD Reagent Buffer. Buffer (48 mL,
pH 7.4), p-hydroxybenzoic acid and sodium azide
(0.4 % w/v).
Stable for > 4 years at 4°C.
Bottle 4: GOPOD Reagent Enzymes. Glucose oxidase
plus peroxidase and 4-aminoantipyrine. Freezedried
powder.
Stable for > 5 years at -20°C.
Bottle 5: D-Glucose standard solution (5 mL, 1.00 mg/mL) in
0.2 % w/v benzoic acid.
Stable for > 5 years at room temperature.
Bottle 6: Control yeast β-glucan preparation (~ 2 g, β-glucan
content stated on the bottle label).
Stable for > 5 years at room temperature.