Oligosaccharide Enzymes in
Sugars Management
NEC White Paper
By: Danielle Harrison, Manager of Scientific and Regulatory Affairs
Oligosaccharides are polymers of simple sugars (monosaccharides).
Polymers of between two and ten sugar units are generally classified
as oligosaccharides, and longer polymers are generally classified
as polysaccharides. The same types of enzymes produce both
oligosaccharides and polysaccharides. Oligosaccharide enzymes
are the enzymes that generate both. This discussion will focus on
enzymes that generate fructose polymers (fructo-oligosaccharides
or FOS) and glucose polymers (gluco-oligosaccharides or GLOS).
These polymers perform a variety of functions in living organisms
and are often attached as side chains to proteins and lipids. They are
especially common in vegetables and cold weather grains, such as
wheat and barley. In humans, the digestible oligosaccharides, such
as sucrose and starch, are a source of energy and blood glucose,
because our bodies have enzymes to digest and absorb them. The
oligosaccharides and longer polymers, such as cellulose, that we
can’t digest are classified as fiber by food scientists. Non-digestible
oligosaccharides may have beneficial effects on constipation,
mineral absorption, lipid metabolism, cancer prevention, hepatic
encephalopathy, glycemia/insulinemia and immunomodulation
(Sweenen 2006).
Unfortunately, processed food often contains more easily and
rapidly digestible oligosaccharides and simple sugars such as
glucose and fructose than we need. The potential consequences
of a steady diet of these easily digestible sugar sources are
weight gain and excessive blood sugar absorption. Emerging
October 2012
science associates these conditions with higher risk of digestive
problems, obesity, dyslipidemia, type II diabetes, liver disease,
cardiovascular disease, cancer and a weakened immune system.
It is interesting that these are almost exactly the beneficial
areas of non-digestible oligosaccharides. Consumption of more
oligosaccharide-producing enzymes along with meals is one tool
that may be beneficial in glucose and weight management. There
are currently two oligosaccharide producing enzymes with New
Dietary Ingredient (NDI) applications on file with the U.S. FDA. These
are transglucosidase and levansucrase.
Transglucosidase is an enzyme that works in a very similar manner
to glucoamylase (amyloglucosidase). Glucoamylase breaks down
starch by cleaving the saccharide bonds of glucose and releasing
glucose. Transglucosidase does the same thing initially, but instead
of simply releasing the glucose, it attaches the glucose to another
saccharide containing molecule. This can be a monosaccharide, such
as glucose or another saccharide polymer. The selectivity is driven by
the relative target concentrations: the three-dimensional structure
of the enzyme and the size of the target molecules. Different
transglucosidase enzymes can produce different bonds and have
different preferences. If you were to measure the glucoamylase
activity in the standard USP/FCC units, you could not distinguish
between a glucoamylase enzyme and a transglucosidase enzyme
because the assay only measures the breakdown of the glucose
bond, not where the glucose breakdown product ends up. Similarly,
transglucosidase activity in the USP/FCC amylase assays would
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not be distinguishable because those assays only measure the
destruction of the starch complex, not what results.
The particular transglucosidase that is currently available for
supplementation is of interest because the bond formation it
catalyzes is of a structure that is difficult for humans to digest and
absorb. When starch is consumed with this enzyme, it removes
some of the glucose from the starch complex and attaches it to a
glucose containing molecule. This glucose-glucose bond is resistant
to digestion. This effectively makes the glucose removed from the
starch not digestible by our bodies as well as the glucose it attaches
to. If it is not digested, it is not absorbed. If it is not absorbed, it
reduces glucose absorbed as well as the calories absorbed. The
bound glucose then also contributes to the fiber load.
The benefits of adequate fiber are well-known in health and weight
management, but the benefits as a prebiotic are less recognized. The
non-digestible oligosaccharides are available to support the growth
of healthy probiotic bacteria in our intestines, which have evolved
to exploit this unused resource synergistically. So by ingesting
transglucosidase enzymes with starch, you effectively reduce the
glucose available for absorption, reduce the calories available
for absorption, increase the fiber content of your intestinese and
support the healthy flora in your intestines.
An interesting formulation opportunity arises from the fact
that transglucosidase will polymerize the glucose with other
monosaccharides and saccharide polymers. If other digestive
enzymes are included in a formula to speed the release of both the
starch and other potential receiving substrates, it should increase
the opportunity for tying up additional glucose. This is because
more starch will be available as an input, and there will be a higher
concentration of targets to bond the glucose.
The other oligosaccharide producing enzyme that currently
has an NDI is levansucrase. Levansucrase removes a fructose
from the dissaccharide sucrose and attaches the fructose to
an oligosaccharide. Differententiating levansucrase by USP/
FCC assays is similar to the situation with glucoamylase and
transglucosidase. Levansucrase and invertase (sucrase) activity
cannot be distinguished by the USP/FCC invertase assay, because
the assay only measures the rate in terms of glucose produced. It
doesn’t look at whether fructose is released or where it goes. The
particular levansucrase available with an NDI can use some other
fructose-containing sugars as substrates as well, but its activity
is quantified in terms of levansucrase. The additional sugar side
activities makes it more useful. This levansucrase also produces
non-digestible oligosaccharides like the transglucosidase, tying up
the fructose from the sucrose molecule while releasing the glucose.
As with the transglucosidase, this effectively reduces the sugar easily
available for absorption. Reduced sugar absorbed results in fewer
calories absorbed. The resulting digestion resistant oligosaccharide
increases the intestinal fiber levels and supports probiotic
growth. Like transglucosidase, similar synergistic opportunities
are available in formulations with other digestive enzymes. In
addition, a combination of transglucosidase and levansucrase may
also be synergistic, since glucose and fructosyl oligosaccharide
produced by the levansucrase can be receptors for the glucose from
transglucosidase, and remnants of the starch polymer and glucosyl
oligosaccharide from the transglucosidase reaction can be receptor
substrates for the levansucrase reaction.
The inter-related reactions, substrates and reaction products
can get pretty complicated, but the bottom line is that adding
oligosaccharide enzymes to a meal should reduce the sugars and
thus the calories absorbed. This was demonstrated in at least two
human clinical studies with the transglucosidase enzyme.
The potential health maintenance benefits of the oligosaccharide
producing enzymes makes them a useful tool in the enzyme arsenal,
especially for people concerned about sugar management, weight
management, fiber intake and general health management.
They also make useful adjuncts to probiotic products, weight
management products and digestive support products.
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