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Levansucrase

Levansucrase is an extracellular enzyme that catalyzes the transfer of fructosyl units from sucrose to growing fructan chains, producing levans, which are β-2,6-linked fructans. It is a member of glycoside hydrolase family 68 and is commonly referred to by itsEC number 2.4.1.10. In addition to transfructosylation, levansucrase can hydrolyze sucrose to glucose and fructose; the relative ratio of transferase to hydrolase activity depends on substrate concentration, pH, and source organism.

Levansucrases are produced by various Gram-positive bacteria, most famously Bacillus subtilis, where the SacB gene encodes

Typical levansucrases are monomeric enzymes of roughly 60–70 kDa, with a signal peptide for secretion. They

Applications include industrial production of levan for food, cosmetic and pharmaceutical use, and exploration of prebiotic

the
secreted
levansucrase.
The
SacB
protein
has
been
widely
used
as
a
negative
selection
marker
in
molecular
genetics:
expression
in
the
presence
of
sucrose
is
lethal
due
to
levan
production.
have
optimum
activity
under
mild
acidic
to
neutral
pH
and
moderate
temperatures,
though
exact
conditions
vary
by
species
and
preparation.
The
products
are
mainly
high-molecular-weight
levans,
though
branching
patterns
can
vary
with
reaction
conditions.
oligosaccharides.
In
research,
levansucrase
is
studied
for
enzyme
mechanism,
structural
features
of
GH68
fructosyltransferases,
and
for
engineering
specificity
towards
various
acceptors.