The Journal of Chemical Physics,
Journal Year:
2024,
Volume and Issue:
161(19)
Published: Nov. 20, 2024
Carbohydrates
constitute
one
of
the
key
classes
biomacromolecules,
yet
vibrational
spectroscopic
studies
involving
carbohydrates
remain
scarce
as
spectra
are
highly
congested
and
lack
significant
marker
vibrations.
Recently,
we
introduced
characterized
a
thiocyanate-labeled
glucose
[Gasse
et
al.,
J.
Chem.
Phys.
158,
145101
(2023)]
demonstrating
2D-IR
spectroscopy
using
probes.
Here,
build
on
that
work
test
azide
groups
alternative
for
to
expand
available
set
local
Many
common
with
different
labeling
positions,
such
galactose,
glucose,
or
lactose,
readily
due
their
application
in
click
chemistry
hence
do
not
require
additional
complex
synthesis
strategies.
In
this
work,
have
azide-labeled
glucose,,
acetylglucosamine
lactose
water
IR
potential
future
applications
carbohydrate-protein
interactions.
Our
findings
indicate
absorption
profiles
dynamics
primarily
determined
by
position
ring.
However,
also
observe
variations
between
samples
same
position.
Furthermore,
demonstrate
usage
remains
feasible
at
biologically
relevant
concentrations,
highlighting
probe
more
biological
processes,
i.e.,
enzymatic
catalysis.
Journal of the American Chemical Society,
Journal Year:
2025,
Volume and Issue:
unknown
Published: Jan. 23, 2025
Visible
light-driven
pyridoxal
radical
biocatalysis
has
emerged
as
a
new
strategy
for
the
stereoselective
synthesis
of
valuable
noncanonical
amino
acids
in
protecting-group-free
fashion.
In
our
previously
developed
dehydroxylative
C–C
coupling
using
engineered
PLP-dependent
tryptophan
synthases,
an
enzyme-controlled
unusual
α-stereochemistry
reversal
and
pH-controlled
enantiopreference
were
observed.
Herein,
through
high-throughput
photobiocatalysis,
we
evolved
set
stereochemically
complementary
PLP
enzymes,
allowing
both
l-
d-amino
with
enhanced
enantiocontrol
across
broad
pH
window.
These
newly
acid
synthases
permitted
use
range
organoboron
substrates,
including
boronates,
trifluoroborates,
boronic
acids,
excellent
efficiency.
Mechanistic
studies
unveiled
unexpected
racemase
activity
earlier
enzyme
variants.
This
promiscuous
was
abolished
shedding
light
on
origin
enantiocontrol.
Further
mechanistic
investigations
suggest
switch
proton
donor
to
account
stereoinvertive
formation
highlighting
stereoinversion
mechanism
that
is
rare
conventional
two-electron
enzymology.
Chemical Reviews,
Journal Year:
2025,
Volume and Issue:
unknown
Published: Feb. 12, 2025
Genetic
code
expansion
(GCE)
in
mammalian
cells
has
emerged
as
a
powerful
technology
for
investigating
and
engineering
protein
function.
This
method
allows
the
precise
incorporation
of
rapidly
growing
toolbox
noncanonical
amino
acids
(ncAAs)
into
predefined
sites
target
proteins
expressed
living
cells.
Due
to
minimal
size
these
genetically
encoded
ncAAs,
wide
range
functionalities
they
provide,
ability
introduce
them
freely
at
virtually
any
site
by
simple
mutagenesis,
this
holds
immense
potential
probing
complex
biology
next-generation
biotherapeutics.
In
review,
we
provide
an
overview
underlying
machinery
that
enables
ncAA
mutagenesis
how
are
developed.
We
have
also
compiled
updated
list
ncAAs
been
successfully
incorporated
Finally,
our
perspectives
on
current
challenges
need
be
addressed
fully
harness
technology.
The Journal of Chemical Physics,
Journal Year:
2024,
Volume and Issue:
161(12)
Published: Sept. 27, 2024
The
nitrile
(C≡N)
stretching
vibration
is
widely
used
as
a
site-specific
environmental
probe
of
proteins
and,
such,
many
computational
studies
have
been
to
investigate
the
factors
that
affect
its
frequency
(νCN).
These
studies,
most
which
were
carried
out
in
ground
electronic
state
molecule
interest,
revealed
formation
normal
or
linear
hydrogen
bond
(H-bond)
with
group
results
blueshift
νCN.
Recently,
however,
several
experimental
showed
for
certain
aromatic
nitriles,
solvent
relaxations
their
excited
state(s)
induce
redshift
(blueshift)
νCN
protic
(aprotic)
solvents,
suggesting
effect
hydrogen-bonding
(H-bonding)
interactions
on
may
depend
molecule.
To
test
this
possibility,
herein
we
combine
molecular
dynamics
simulations
and
quantum
mechanical
calculations
assess
H-bonding
5-cyanoindole
(5-CNI)
different
states.
We
find
C≡N
can
form
either
one
H-bond
(single-H-bond)
two
H-bonds
(d-H-bonds)
molecules
state,
single-H-bond
lead
shift
higher
lower
frequency,
depending
angle,
consistent
previous
whereas
d-H-bonds
cause
redshift.
However,
lowest-lying
(i.e.,
S1),
has
characteristics
charge-transfer
all
νCN,
being
effective
regard.
Analytical Chemistry,
Journal Year:
2025,
Volume and Issue:
unknown
Published: Jan. 10, 2025
Two-dimensional
infrared
(2D
IR)
spectroscopy
is
a
powerful
technique
for
measuring
molecular
heterogeneity
and
dynamics
with
high
spatiotemporal
resolution.
The
methods
can
be
applied
to
characterize
specific
residues
of
proteins
by
incorporating
frequency-resolved
vibrational
labels.
However,
the
time
scale
that
2D
IR
measure
limited
label's
excited-state
lifetime
due
decay
absorption
bands.
To
extend
this
scale,
labels
longer
lifetimes
are
sought.
An
effective
approach
inhibiting
intramolecular
energy
relaxation
isolate
vibration
from
rest
molecule
inserting
heavy
atom
bridge.
Although
strategy
has
been
demonstrated
through
generation
functionalized
amino
acids,
straightforward
route
their
selective
incorporation
into
often
unclear.
A
facile
attachment
cyano
group
at
cysteine
generate
thiocyanate
contributed
its
adoption
as
label
proteins.
We
demonstrate
an
analogous
used
introducing
cyanoselenocysteine
selenocyanate
containing
heavier
bridge
atom.
confirm
pump–probe
100–250
ps,
depending
on
solvent,
which
enable
collection
spectra
frequency
scales.
The Journal of Physical Chemistry B,
Journal Year:
2025,
Volume and Issue:
unknown
Published: Jan. 13, 2025
Fermi
resonance
is
a
common
phenomenon,
and
hidden
caveat
exists
in
the
applications
of
infrared
probes,
causing
spectral
complication
shorter
vibrational
lifetime.
In
this
work,
using
cyanotryptophan
(CNTrp)
side
chain
model
compound
5-cyanoindole
(CN-5CNI),
we
performed
Fourier
transform
spectroscopy
(FTIR)
two-dimensional
(2D-IR)
on
unlabeled
12C14N-5CNI
its
isotopically
labeled
substituents
(12C15N-5CNI,
13C14N-5CNI,
13C15N-5CNI)
demonstrated
existence
5CNI.
By
constructing
Hamiltonian
simulating
2D-IR
spectra,
show
that
distinct
patterns
various
isotope
are
determined
by
quantum
mixing
consequences
at
v
=
1
state,
as
well
2
where
coupling
anharmonicity
play
crucial
role.
Our
work
provides
important
insights
into
elusive
type
resonance,
much
smaller
than
anharmonicity,
which
termed
weak
case.
The Journal of Physical Chemistry B,
Journal Year:
2025,
Volume and Issue:
unknown
Published: March 6, 2025
It
has
been
shown
that
4-cyanoindole-2'-deoxyribonucleoside
(4CNI-NS)
is
a
versatile
spectroscopic
probe
of
DNA
structure
and
dynamics,
as
it
can
pair
with
all
four
natural
bases.
However,
its
photophysics
have
not
examined
in
detail.
Herein,
we
employed
multiple
techniques,
including
static
fluorescence
spectroscopy,
time-resolved
transient
infrared
theoretical
calculations,
to
assess
the
photophysical
properties
this
nucleoside
analogue
series
solvents.
We
found
(1)
large
quantum
yield
(0.85
±
0.10)
relatively
long
decay
lifetime
(10.3
1.0
ns)
H2O,
both
which
become
smaller
other
solvents
examined,
(2)
maximum
emission
frequency
exhibits
linear
dependence
on
relative
polarity
index
solvent,
(3)
oscillator
strength
C≡N
stretching
vibration
increased
by
factor
>10
upon
transition
excited
electronic
state
(S1),
(4)
besides
solvent
relaxation,
rotational
motion
around
single
bond
connecting
pentose
group
indole
ring
also
present
S1
state,
(5)
aprotic
processes
lead
(νESA)
shift
toward
higher
frequencies,
whereas
protic
effects
these
are
more
complex.
Taken
together,
findings
provide
molecular
basis
for
interpreting
signals
practical
applications.
European Journal of Organic Chemistry,
Journal Year:
2025,
Volume and Issue:
unknown
Published: March 11, 2025
Abstract
Amino
acids
play
significant
roles
in
the
study
of
life
sciences,
pharmaceutical
R&D,
bioengineering,
and
so
on.
Artificial
amino
acid‐based
drugs
are
important
advancing
therapeutic
innovation
for
multiple
diseases
including
chronic
pain,
diabetes,
Alzheimer's
disease.
On
other
hand,
multicomponent
reactions
(MCRs)
demonstrated
to
be
a
powerful
strategy
construction
complicated
structures
from
readily
accessible
starting
reagents
one
pot.
Thus,
applying
preparation
their
derivatives
can
potent
research
chemistry.
With
rapid
development
various
catalytic
methods
reactions,
this
review
outlines
recent
acid
by
transition
metal‐catalyzed,
light‐mediated
organocatalytic
reactions.
