CloverDirect™ tRNA Reagents for Site-Directed Protein Functionalization
Background:
CloverDirect™ tRNA Reagents for Site-Directed Protein Functionalization allow the incorporation of unnatural amino acids at defined positions of proteins using in vitro translation. Unnatural amino acids containing fluorescent groups, biotin, PEG, photo-crosslink, etc are available. Proteins with unnatural amino acids will be obtained within a few hours just by adding CloverDirect™ reagents and DNA template having an amber stop codon (UAG) or a four-base codon (CGGG) to an in vitro translation system. CloverDirect™ covers the following four applications. In addition, we provide custom services for the expression of proteins with unnatural amino acids (contact us).
It is not easy to incorporate fluorescent groups into proteins in a site-direct and quantitative fashion by chemical modification. CloverDirect™ tRNA Reagents for Site-Directed Fluorescence Labeling allow the incorporation of fluorescent unnatural amino acids into proteins in a site-direct and quantitative fashion. Various fluorescent dyes are available including those for 488 nm, 543 nm and 633 nm excitation.
Site-Directed Biotin Labeling:
CloverDirect™ tRNA Reagents for Site-Directed Biotin Labeling allow the incorporation of biotinylated unnatural amino acids into proteins in a site-direct and quantitative fashion. Labeling proteins are available for the oriented immobilization onto avidin-coated plates and beads. The biotinylated amino acids have one or two aminohexyl liners between amino acid and biotin.
Site-Directed Post-Translational Modification:
It is not easy to prepare post-translationally modified proteins (phosphorylation, methylation, etc.). CloverDirect™ tRNA Reagents for Site-Directed Post-Translational Modification allow the incorporation of modified amino acids into proteins to obtain post-translationally modified proteins in a site-direct and quantitative fashion.
Site-Directed Unnatural Mutagenesis:
By incorporation of unnatural amino acids containing functional groups, novel functional proteins can be designed and synthesized. CloverDirect™ tRNA Reagents for Site-Directed Unnatural Mutagenesis allow the incorporation of unnatural amino acids with PEG, photo-crosslinking, photo-isomerizable groups, etc.
Principe:
Principe
of
incorporation
of
unnatural
amino
acids
Incorporation
position
of
unnatural
amino
acids is
defined
by a UAG
amber
codon or
CGGG
four-base
codon.
An
unnatural
aminoacyl-tRNA
recognizes
the UAG
amber
codon or
the CGGG
codon
during
translation.
Consequently,
the
unnatural
amino
acid is
incorporated
at the
directed
site of
the
protein.
By using
two
tRNAs
for
amber
and
four-base
codons,
dual-labeled
proteins
can be
obtained
which
are
available
for
fluorescence
resonance
energy
transfer
(FRET).
UAG
amber
codon
If
the UAG
codon is
recognized
by the
amber
suppressor
tRNA,
full-length
protein
containing
the
unnatural
amino
acid is
successfully
synthesized.
On the
contrary,
if the
UAG
codon is
recognized
by
release
factor 1
(RF1)
which is
one of
the
termination
factors,
the
protein
synthesis
is
terminated.
Therefore,
the
translation
product
obtained
as a
full-length
protein
contains
the
unnatural
amino
acid at
100%
efficiency.
CGGG
four-base
codon
If the
CGGG
codon is
recognized
by the
four-base
anticodon
tRNA,
full-length
protein
containing
the
unnatural
amino
acid is
successfully
synthesized.
On the
contrary,
if the
CGG is
recognized
as a
triplet
codon by
Arg-tRNA,
the
reading
frame
shifts
to +1
frame
and a
downstream
stop
codon
terminates
the
protein
synthesis.
Therefore,
the
translation
product
obtained
as a
full-length
protein
contains
the
unnatural
amino
acid at
100%
efficiency.
Kit component:
Unnatural
aminoacyl-tRNA
X 1
tRNA
dissolving
buffer
X
1
Note 1 : One tube contains unnatural aminoacyl-tRNA sufficient for 300 µL of in vitro translation reaction. Once thawed, unnatural aminoacyl-tRNA can be stored at -70 ?C for 2 months.